Wave guide with isolated coupling interface

ABSTRACT

A wave-guide having an isolated coupling interface. In one variation, a constant negative pressure is maintained around the area surrounding the wave-guide. Coupling liquid may be directed to the tip of the wave-guide to provide the coupling interface between the wave-guide and a source fluid container. The suction from the constant negative pressure may remove excess coupling liquid and isolating the coupling liquid to the area around the tip of the wave-guide. The wave-guide assembly may also include mechanisms for adjusting the volume of fluid at the tip of the wave-guide. When the position of the wave-guide is displaced, fluid compensation mechanism may increase or decrease the volume of fluids at the distal end of the wave-guide to maintain proper coupling between the wave-guide and the source fluid container. Methods for utilizing negative pressure around the distal end of the wave-guide to isolate the coupling liquid are also described.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is claiming the benefit of priority to U.S.provisional application Ser. No. 60/429,778 entitled “WAVE GUIDE WITHISOLATED COUPLING INTERFACE” filed on Nov. 27, 2002, U.S. provisionalapplication Ser. No. 60/434,756 entitled “WAVE GUIDE WITH ISOLATEDCOUPLING INTERFACE” filed on Dec. 18, 2002, and U.S. provisionalapplication Ser. No. 60/435,767 entitled “APPARATUS FOR HIGH-THROUGHPUTNON-CONTACT LIQUID TRANSFER AND USES THEREOF” filed on Dec. 19, 2002,each of which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

[0002] The present invention generally relates to acoustic dropletejection systems and in particular to an improved coupling interfacedesign for use in an acoustic droplet ejection system.

DESCRIPTION OF RELATED ART

[0003] Many methods for the precision transfer and handling of fluidsare known and used in a variety of commercial and industrialapplications. However, most of these methods require the direct contactof transfer device with the source fluid, thus increasing the risk ofcross contamination between various fluid sources. The presentlyburgeoning industries of biotechnology and biopharmaceuticals areparticularly relevant examples of industries requiring ultra-pure fluidhandling and transfer techniques. Not only is purity a concern, currentbiotechnological screening and manufacturing methods also require highthroughput to efficiently conduct screening of compound libraries,synthesis of screening components, and the like.

[0004] Fluid transfer methods that require contacting the fluid with atransfer device, e.g., a pipette, a pin, or the like, dramaticallyincrease the likelihood of contamination. Many biotechnology procedures,e.g., polymerase chain reaction (PCR), have a sensitivity that resultsin essentially a zero tolerance for contamination. Accordingly, anon-contact method for fluid transfer would result in a drasticreduction in opportunities for sample contamination.

[0005] Furthermore, fluid transfer methods that require physical contactwith source fluids also require elaborate mechanical controls andcleaning mechanisms, and do not conveniently and reliably produce thehigh efficiency, high-density arrays.

[0006] Biotechnology screening techniques may involve many thousands ofseparate screening operations, with the concomitant need for manythousands of fluid transfer operations in which small volumes of fluidare transferred from a fluid source (e.g., a multi-well platecomprising, for example, a library of test compounds) to a target (e.g.,a site where a test compound is contacted with a defined set ofcomponents). Thus, not only the source, but also the target may comprisethousands of loci that need to be accessed in a rapid,contamination-free manner.

[0007] Similarly, biotechnology synthesis methods for the generation oftools useful for conducting molecular biology research often requiremany iterations of a procedure that must be conducted withoutcontamination and with precision. For example, oligonucleotides ofvarying lengths are tools that are commonly employed in molecularbiology research applications, as, for example, probes, primers,anti-sense strands, and the like. Traditional synthesis techniquescomprise the stepwise addition of a single nucleotide at a time to agrowing oligomer strand. Contamination of the strand with an erroneouslyplaced nucleotide renders the oligonucleotide useless. Accordingly, anon-contact method for transferring nucleotides to the reaction site ofa growing oligomer would reduce the opportunity for erroneous transferof an unwanted nucleotide that might otherwise contaminate a pipette orother traditional contact-based transfer device.

[0008] In order to meet these needs, methods have been developedutilizing acoustic waves to eject fluids out of source reservoirs. Theacoustic droplet ejection systems allow for a non-contact method for theprecision-transfer of small amounts of fluid in a rapid manner that iseasily automated to meet industry needs. An exemplary non contact systemfor ejecting liquid droplets to a target location is described in U.S.patent application, Publication Ser. No. 2002/0,094,582 A1, publishedJul. 18, 2002, entitled “Acoustically Mediated Fluid Transfer MethodsAnd Uses Thereof” and it is incorporated herein by reference in itsentirety.

[0009] However, a major obstacle in developing a reliable andcost-effective fluid ejection system lies in the development of anappropriate coupling interface for the wave-guide. As seen in FIG. 2 ofthe U.S. patent application Publication Ser. No. 2002/0,094,582,coupling medium 20 is distributed across the entire bottom surface offluid containment structure 30. This may increase the difficulty inchanging fluid containment structure and changing alignment of theacoustic liquid deposition emitter. Dispersion or wicking of couplingfluid from the edge of the source fluid containment structure may alsobe a problem in this design.

[0010] Another example of non contact system for ejecting liquiddroplets to a target location is described in U.S. patent application,Publication Ser. No. 2002/0,037,359 A1, published Mar. 28, 2002,entitled “Focused Acoustic Energy In The Preparation of Peptide Arrays.”As seen in FIG. 1 of the Ser. No. 2002/0,037,359 publication, thecoupling medium 41 extends beyond the edges of the reservoir or fluidcontainment structure. The structure described in this application makesit difficult to replace or change source fluid containment structurewithout inadvertently spilling or splattering the coupling liquid sincethe coupling medium is not isolated. In addition, since the couplingmedium 41 expands across the base 25 of the reservoir, it is alsodifficult reposition the acoustic radiation generator 35 whilemaintaining the coupling interface provide by the coupling medium 41.

[0011] Yet another example of the droplet ejection systems which utilizeacoustic energy is U.S. Pat. No. 4,751,530 issued Jun. 14, 1988 to Elrodet al. The '530 patent describes an acoustic print head 11 having anarray of spherical lenses 12 a-12 i. The print head 11 is submerged in apool of ink 16, as shown in FIG. 2. The lenses 12 a-12 i may beacoustically isolated from each other “such as by providing narrow slots66 between them which are filled with air or some other medium having anacoustic impedance which differs significantly from the acousticimpedance of the substrate 22 such that an acoustic mismatch iscreated.” See col. 5, line 62 to col. 6, line 8 and FIGS. 7-8 of U.S.Pat. No. 4,751,530. The slots 66 however do not extend the fullthickness of substrate 22 nor do the slots surround each side of thesubstrate 22. Thus, there is no full isolation of the wave-guide oracoustic propagation path. Because this design requires that theacoustic wave generation units be immersed in the source fluid,different fluids would require separate wave generation and propagationpaths positioned in each pool of fluid. Another associated consequenceof immersing the acoustic wave generation unit in the source fluid isthat the same wave generation and propagation unit can not be used withseparate fluid containment structures without the risk of crosscontamination. In addition, since this particular design requires thesource fluid to be distributed over an array of emitters, it does notneed nor suggest the use of a coupling interface.

[0012] Existing non-contact liquid transfer systems are limited and donot provide for high-throughput transfer of liquids and their ability togenerate high-density arrays in an efficient and reliable manner arealso limited. A system that is capable of transferring a large number ofliquids from their receptive locations in a high density array to targetlocations comprise of another high density array in a predeterminedpattern with precision, not only may be used for generating high-densityarrays for screening or synthesis of chemical compound, the systemitself may be implemented as the platform for synthesis and/orscreening.

[0013] Accordingly, there exists a need in the art for a non-contactmethod for the precision transfer of small amounts of fluid in a rapidmanner that is easily automated to meet industry needs. A system that iscapable of efficient transfer of liquids from any location in a firstset of well plates to a second set of well plates in any order andpattern, may provide significant advantages in high-throughput liquidtransfer, high-throughput biological/chemical/biochemical synthesisand/or high-throughput screening of biological/chemicals/biochemicalcompounds.

SUMMARY OF THE INVENTION

[0014] Accordingly, the invention in one embodiment provides an acousticwave source, which is capable of ejecting liquid from a pool of sourceliquid onto a target location. Another embodiment of the presentinvention provides for a mechanism to align any location in an array orarrays of source fluid pools with any location in an array or arrays oftarget locations, such that liquid may be transferred from any locationin the source liquid array or arrays to any location in the targetlocation array or arrays. Yet another embodiment of the presentinvention provides an image detection system for controlling and/ormonitoring the fluid transfer between the source liquid array and thetarget location array. The image detection system may be implemented foraligning a source liquid array with a target location array, monitoringthe transfer of liquid, or monitoring/recording reactions/conditionwithin the target location after the completion of liquid transfer.Various other embodiments and advantages of the present invention willbecome apparent to those skilled in the art as more detailed descriptionis set forth below.

[0015] In one aspect of the present invention, an integrated system isprovided for non-contact transfer of small amounts of liquid materialsfrom source vessels (or source fluid containment structures) to targetvessels (or target devices, plates or surfaces). “Non-contact,” as usedherein, means that a source liquid is transferred or removed from asource pool of liquid without contacting the source liquid with atransfer device. Because energy waves, such as acoustic waves, are usedto force one or more drops of liquid out of the source pool and into atarget region, no physical device needs to come into contact with thesource pool to effectuate the transfer of the liquid.

[0016] In another aspect of the invention, an apparatus is provided forrandom-access liquid transfer. The random-access liquid transfercapability may allow transfer of a liquid from any location within amatrix of source fluid vessels to any location within a matrix oftargets. For example, the source vessels may comprise a series of wellplates, and the target vessels may comprise a separate series of wellplates. Liquids from different wells (which may be from the same plateor a different plate) may be transferred to different or same targetwells (which may be from the same plate or different plate) one afteranother in any sequence or pattern that is prescribed by the user.Unlike most system on the market, which require linear sequential accessof source materials and has a predefined pattern of delivery to thetarget locations, this apparatus may allow non-linear and/or randomaccess of both source liquid pools and target locations. That is to say,the user may eject fluid from any source liquid location in the sourcevessels into any target location in the target vessels, and the nextsource fluid location and target location may also be any source liquidlocation and any target location in their receptive arrays of vessels.The selection of the source liquid location and target location iscompletely independent of the previous source/target locationselections.

[0017] In yet another aspect of the invention, the fluid transferapparatus may allow transfer of predefined volume of liquids from asource vessel to a target vessel. The apparatus may be designed suchthat in a series of ejections, different volumes of liquid aretransferred in each ejection. The user may also program the apparatus todeliver a series of liquid droplets of various sizes that are predefinedby the user. As it will be apparent to one skilled in the art, variousvariations of the apparatus may be utilized for drug discovery orchemical synthesis.

[0018] In one variation, the non-contact, random-access liquid transferapparatus is comprised of a) an acoustic emitter device, b) two X/Ylinear stage assemblies, c) two handling devices, one each attached tothe X/Y stage assemblies, d) two storage queues, one for source vesselsand the other for target devices, e) a image detection system, f)machine controls, electronics and software, g) frame and supportstructure, and h) environment and safety enclosure. All of the system'ssub-assemblies and components may be built upon an internalskeleton-like framework. Alternatively, the deferent sub-assemblies andcomponents may be positioned by separate frame or supporting structure.

[0019] The acoustic emitter may provide the energy waves for ejectingliquid out of a source vessel and onto a target device. The X/Y linearstage assemblies along with their corresponding handling device mayretrieve source vessel and target device from the storage queues andalign the source vessel and the target device above the acousticemitter. The storage queues may hold multiple source vessels and targetdevice, and may be capable of delivery any of the source vessels ortarget devices to a predefined location where specific source vessel ortarget device may be accessed by the handling device attached to its X/Ylinear stages. The image detection system may provide signal feedback tothe machine controls so that appropriate alignment of source vessel andtarget vessel with the acoustic emitter may take place. The image systemmay be used for pre-ejection calibration, and it also may be implementedto monitor the ejection process. Furthermore, the image system may alsobe used for post ejection verification/measurements of physical and/orchemical parameters within each individual target location. Machinecontrols, electronic and software, may provide overall control of thevarious components within the liquid transfer apparatus. The machinecontrols may provide feedback control so that appropriate source vesseland target device are retrieved from the storage queue and positionedabove the acoustic emitter appropriately. The machine controls mayfurther define the amount of energy delivered by the acoustic emitterand the location of the focus of the acoustic wave been emitted. Asoftware algorithm may be implemented along with machine controls suchthat specific source/target alignment and ejection sequence is followedin a high-throughput liquid transfer process. A frame and supportstructure may be provided for integrating the various components in theliquid transfer apparatus. Various moving mechanisms may be connected toa primary frame such that alignments and/or calibration may be easilycarried out between various moving parts. An environment and safetyenclosure may be provide to control/monitor various environmentparameters and prevent unintended user intervention during systemoperation. Various design variations may be implemented in the liquidtransfer apparatus.

[a] Acoustic Emitter Device

[0020] An acoustic emitter device is provided for generating andpropagating an acoustic wave in a direction defined by a wave-guide. Thewave-guide may comprise of a continuous piece of wave conducting mediumfor transferring an energy wave from the wave generation source to thecoupling liquid. Alternatively, the wave-guide may comprise a pluralityof interconnecting parts. The wave-guide may further comprise a focusingdevice (e.g. lens) at one end for focusing the energy wave as it exitsthe wave-guide. Materials may be selected for optimizing the transfer ofa particular kind of wave. In one variation, the wave-guide isfabricated with materials for facilitating transfer of an acoustic wave.For example, the acoustic wave-guide may be constructed of aluminum,silicon, silicon nitride, silicon carbide, sapphire, fused quartz,glass, a combination there of, or the like. In one variation, a separatelens may be placed on the distal end of the wave-guide for forming afocused acoustic beam. Alternatively, the distal end of thewave-conducting medium may have a concave surface or other structuralfeatures for facilitating the focus of the wave as it exits thewave-conducting medium. Other wave conducting channels or medium thatare well known to one skilled in the art may also be adapted forconstructing the wave-guide.

[0021] A fluid basin may be provided for supplying coupling liquid tothe distal end of the wave-guide and/or removing excess coupling liquidfrom the area surrounding the wave-guide. The fluid basin may comprise astructure that surrounds the wave-guide and has a channel for supplyingcoupling liquid and a separate channel for providing suction to removeexcess coupling liquid. The “suction channel” is a channel through whichliquid can be removed or withdrawn. A pressure gradient may bemaintained across the two ends of the suction channel to facilitateremoval of the liquid. A vacuum generator or a suction source may beconnected to one end of the suction channel. In another variation, asuction generator, for generating a pressure pocket having a pressurelower than the pressure in the ambient or surrounding environment, maybe attached to one end of the suction channel to facilitate the removalof the liquid from the other end of the suction channel.

[0022] In another variation, the wave-guide may be supported within ahousing. The wave-guide housing and the wave-guide may move as a unit,independent of a fluid basin that provides the coupling liquid and fluidsuction.

[0023] In yet another variation, a coupling liquid outlet surrounds thewave-guide, and a constant negative pressure is maintained around theimmediate area surrounding the coupling liquid outlet. This may beachieved with a vacuum generator to create the negative pressure androuting the negative pressure source to a cavity that surrounds thecoupling liquid outlet. The negative pressure area surrounding thewave-guide may create a suction, which facilitates removal of excesscoupling liquid from the area surrounding the wave-guide.

[0024] Alternatively, the wave-guide may be positioned within a lumen.The lumen may be flooded with coupling liquid so that the tip of thewave-guide is covered with coupling liquid. A constant negative pressuremay then be maintained around the lumen. The constant negative pressuremay also be delivered through a channel surrounding the lumen or througha cavity surrounding the lumen. The channel or lumen may be connected toa negative pressure source. In another variation, two coaxial channelsare implemented for providing the coupling liquid and the suction. Thewave-guide may be positioned within the inner lumen and enough space maybe provided between the walls of the inner lumen and the wave-guide forcoupling liquid to flow. The outer lumen may be connected to a negativepressure source. In the above variations, the wave-guide may be fixedlypositioned within the inner lumen or moveably positioned within theinner lumen.

[0025] A fluid pump may be used to supply fluid to the inner lumen orthe coupling liquid outlet. A fluid reservoir may be connected to afluid pump for supplying the coupling liquid. The fluid pump may be aperistaltic pump, a diaphragm pump, a centrifugal pump, a piston pump, apositive displacement pump or other active fluid transfer mechanismswell known to one skilled in the art. Alternatively, other fluid supplysources, including passive fluid supply sources, may also be implementedto supply fluid to the inner lumen. For example, the coupling liquid maybe provided through gravitational force by displacement of a fluidcontainer at an appropriate height. Connections may be provided for thefluid to flow from the liquid container to the inner lumen or thecoupling liquid outlet. In this variation, the fluid container may be aseparate container from the container for capturing returning couplingliquid from the negative pressure suction.

[0026] The negative pressure source may comprise a mechanical fluidpump, a diaphragm pump, a centrifugal pump, a vacuum generator or otherflow generator well known to one skilled in the art. The negativepressure source may also be created by a siphon, which compresses airthrough a venturi whose throat has an opening to create a low-pressuresource at the throat without the use of any moving mechanical parts.

[0027] It is understood that in this disclosure and related amendmentsthe term “connect” and “connecting,” when used in the context ofestablishing a connection with a fluid source, a vacuum source or apump, may include providing additional medium such as a tubing or achannel to achieve the connection between one element and anotherelement. For example, a fluid pump connected to a channel may include afluid pump that is connected to the channel through tubing to allowfluid transfer between the fluid pump and the channel, or the fluid pumpmay be directly connected to the channel.

[0028] In another variation, the coupling liquid may be supplied to thetip of the wave-guide through one or more channels positioned next tothe wave-guide, and the negative pressure may be provided through one ormore channels positioned next to the coupling liquid supply channels.For example, a coupling liquid outlet may surround the wave-guide, and aplurality of channels may surround the coupling liquid outlet forremoving excess fluid from the distal end of the wave-guide assembly.

[0029] The wave-guide may have a cross-sectional area of 1 square mm to10000 square mm. Preferably, the cross sectional area of the wave-guideis between 2 square mm to 800 square mm. More preferably, the crosssectional area of the wave-guide is between 3 square mm to 150 squaremm. Most preferably, the cross sectional area of the wave-guide isbetween 20 square mm to 25 square mm.

[0030] The coupling liquid cross sectional area above the wave guide ispreferably isolated to an area less than twenty times thecross-sectional area of the wave-guide, more preferably less than tentimes the cross-sectional area of the wave-guide, even more preferablyless than 3 time the cross-sectional area of the wave-guide. Thecoupling liquid area above the wave-guide may be isolated to an areaabout the same as the cross-sectional area of the wave-guide.

[0031] In the variation where a negative pressure surrounds thewave-guide, the area surrounded by the negative pressure region(including the wave guide and negative pressure region itself) ispreferably between 3 square mm to 30000 square mm, more preferablybetween 3 square mm to 150 square mm, even more preferably between 60square mm to 70 square mm. In one variation, the area surrounded by thenegative pressure region is design to be about three times thecross-sectional area of the wave-guide. For example, the wave-guide mayhave a cross-sectional area of 21 square mm and the corresponding areasurrounded by the negative pressure region (including the wave-guide andthe negative pressure region itself) may be 64 square mm. In anothervariation, the area surrounded by the negative pressure region is 1.62times the cross-sectional area of the wave-guide.

[0032] In another aspect of the invention, the wave-guide may bemoveably disposed within the wave-guide assembly such that thewave-guide focus may be adjusted along a linear axis. The wave-guideassembly may comprise of a wave-guide positioned within a fluid basin,and the fluid basin may be configured to supply coupling liquid to thedistal end of the wave-guide. In one variation, a fluid basinsurrounding the wave-guide may be isolated from the wave-guide such thatthe wave-guide may move on a linear path independent of the fluid basin.This may allow the source fluid containment structure to maintain aconstant gap from the fluid basin while the wave-guide focus is beingadjusted. This constant gap may aid in maintaining the fluid couplingwhile the focus of the wave-guide is being adjusted. In addition, thisdesign may also allow higher speed of movements of the source fluidcontainment structure in the X-Y plane, while allowing the source fluidcontainment structure to maintain contact with the coupling liquid.

[0033] The fluid basin surrounding the wave-guide may additionallyinclude a trough for collection of excess coupling liquid that is notcaptured by the outer lumen or suction channel. The trough may be aformed by a lip surrounding the fluid basin. Alternatively, the troughmay comprise a groove surrounding the negative pressure area. A channelfor draining fluids from the trough may be provided. In addition, thisdraining channel may be connected to a negative pressure source forfacilitating removal of fluids in the trough.

[0034] In another aspect of the invention, a fluid compensationmechanism is provided to offset the displacement of the wave-guideduring focus adjustment so that fluid coupling between the tip of thewave-guide and the bottom of the source fluid containment structure maybe maintained. In one variation, the coupling liquid is transferred backand forth through a flow line to a fluid displacement device (e.g.,piston pump). The fluid displacement device may be coupled to thedisplacement mechanism moving the wave-guide to achieve synchronization.For example, the same motor that positions the wave-guide may actuatethe fluid displacement device, so that coupling liquid displacement maybe synchronized with the movement of the wave-guide. In anothervariation, a mechanically separate mechanism may provide the couplingliquid displacement. In addition, an electronic control mechanism may beprovided to control the coupling liquid displacement and the wave-guidedisplacement. For example, a computer may be used to provide control andsynchronization.

[0035] The source fluid containment structures may be well plates ormicrotiter plates that are commonly used in the biotech field, forexample well plates having 384 wells or 1536 wells may be utilized.Other fluid containers such as capillaries (e.g., capillary arrays), aflat plate with isolated regions of liquids, and the like may also beused. Furthermore, the source fluid containment structure may also havechannels or micro-channels embedded in the structure for supplying thewells with source fluids as needed. In addition, gates or valves may beintegrated with these fluid supply paths for controlling the flow and/orthe level of fluids in the wells. Sensors and electronic controlmechanisms may also be implemented for managing the source fluid andmaintaining the fluid levels in the wells.

[0036] A moveable stage may be provided for positioning the source fluidcontainment structure. Actuators, motors, or other displacement devicesmay be implemented with electronic control mechanisms (e.g. a computeror a feed back control circuitry) for positioning and aligning thedesirable well in the source fluid containment structure over thewave-guide after each ejection.

[0037] A frame may be provided for positioning the fluid basin aroundthe wave-guide. The frame may be connected to an independent stage or anexisting structure (e.g., a skeleton framework built into the fluidejection system) in the fluid ejection system. The fluid basin may becoupled to the frame in such a way as to allow some degree of X-Ymovement but no movement in the Z direction. In one variation, bearingsare provided to remove any side loads that could be imparted on thewave-guide due to the fluid basin and wave-guide misalignment, as oneskilled in the art would appreciate.

[0038] A computer or electronic controller may be adapted forsynchronizing different mechanisms in the fluid ejection system and/orcontrolling the size and direction of the ejection. The computer may beprogrammed to eject fluids out of selected wells on the source fluidcontainment structure in a particular sequence. Feedback mechanisms,such as sensors or other detectors, may be implemented in the computercontrolled fluid ejection system to improve the performance andcapability of the system.

[0039] A method for utilizing a negative pressure area or suctionsurrounding a wave-guide for isolating the coupling liquid is alsocontemplated in this disclosure. In one variation, the method includesthe process of providing a wave-guide, supplying a coupling liquid tothe distal end of the wave-guide, maintaining a negative pressure in anarea surrounding the wave-guide to remove excess coupling liquid,directing an acoustic wave through the wave-guide toward the distal endof the wave-guide, and allowing the acoustic wave to pass through thecoupling liquid, the source containment structure and into the sourcefluid. In another variation, the method further includes repositioningof a source fluid containment structure (e.g., a well plate) above thewave-guide to allow ejection of a different source fluid from adifferent reservoir in the source fluid containment structure. In yet,another variation, the position of the wave-guide may be adjusted toreposition the focus point of the acoustic wave, and may further includefluid displacement device for making appropriate compensation to thevolume of the coupling liquid on top of the wave-guide in order tomaintain the coupling between the wave-guide and the source fluidcontainment structure. The method may also include the step ofmaintaining a constant distance between the fluid basin and the bottomsurface of the source fluid containment structure as the source fluidcontainment structure is re-positioned between individual reservoirscontaining source fluids.

[b] Droplet Steering Mechanism

[0040] In another aspect of the invention, a droplet steering mechanismmay be integrated within the non-contact liquid transfer apparatus tomaintain, correct or adjust the trajectory of liquid ejected out of thesource liquid container. The steering mechanism may be placed betweenthe source liquid container and the target device to assist the ejectedliquid to reach its intended target. The steering mechanism may also bealigned with the acoustic ejector to maintain or adjust the flight pathof the ejected droplet so that the ejected droplet may stay on theZ-axis of the system.

[0041] In one variation, gas or air flow is directed through a throatedstructure to steer the trajectory of the ejected liquid droplet. Forexample, the throated structure may comprise a nozzle defining a throat,which may have an inlet or entrance port and a preferably smaller outletor exit port. A venturi structure may also be used, in which case theinlet or entrance port may open into a nozzle which converges to anarrower throat and reopens or diverges into a larger outlet or exitport.

[0042] In the case of a nozzle defining a throat having an inlet orentrance port and a smaller outlet or exit port, the throat preferablyconverges from a larger diameter inlet to a smaller diameter outlet.Through this throat, a vectored or directed gas or air stream may bedirected into the inlet to be drawn through the structure. The gas orair stream is preferably driven through the system via a pump, either apositive or negative displacement pump, such as a vacuum pump. The gasor air stream may also pass through a heat exchanger that is connectedto the nozzle. The heat exchanger may be used to maintain or change thetemperature of the gas or air stream. This in turn may be used tocontrol the temperature of the droplets through convective heating orcooling as the droplets traverse through the nozzle. As the gas or airstream approaches the outlet, the gas or air may increase in velocityand is preferably drawn away from the centerline of the nozzle through aconnecting deviated air flow channel. The gas or air stream may be drawnaway from the throat at a right angle from the centerline of the nozzleor at an acute angle relative to the nozzle centerline. The gas or airstream may then continue to be drawn away from the throat and eithervented or recycled through or near the inlet again. The gas used maycomprise of various gases well known to on skilled in the art that aresuitable for displacing liquids (e.g. nitrogen, carbon-dioxide, helium,etc. or a combination thereof). The gas may comprise any number ofpreferably inert gases, i.e., gases that will not react with the dropletor with the liquid from which the droplet is ejected. The gas may alsocomprised of several gases, a single gas, or a mixture of gas or airwith other micro-particles or liquid mist. However, a gas that is highlyreactive with the ejected liquid droplet may also be used. This reactivegas may comprise of several compounds, a single compound, or a mixtureof gas or air with other micro-particles or fine liquid mist.

[0043] A droplet ejected from the surface of a liquid will typicallyhave a first trajectory or path. The liquid is preferably contained in awell or reservoir disposed below the nozzle. To prevent overheating ofthe liquid within the reservoir during droplet ejection, the temperatureof the well plate may be controlled actively, e.g., through conductivethermal heating or cooling, or the droplet generator may be usedindirectly to control the temperature of each of the wells duringdroplet ejection. If the trajectory angle of the droplet relative to acenterline of the inlet nozzle is relatively small, i.e., less than afew tenths of a degree off normal, the droplet may pass through theoutlet and on towards a target with an acceptable degree of accuracy. Ifthe trajectory angle of the droplet is relatively large, i.e., greaterthan a few degrees and up to about ±22.5°, the droplet may be consideredas being off target.

[0044] As the droplet enters the inlet off-angle and as it advancesfurther up into the structure, the droplet is introduced to the highvelocity gas or air stream at the perimeter of the interior walls of thenozzle. The gas or air stream accordingly steers or redirects themomentum of the droplet such that it obtains a second or correctedtrajectory which is closer to about 0° off-axis. The gas or air streamat the connecting deviated air flow channel is preferably drawn awayfrom the centerline of the nozzle and although the droplet may besubjected to the gas or air flow from the connecting deviated air flowchannel, the droplet has mass and velocity properties that constrain itsability to turn at right or acute angles when traveling at a velocity,thus the droplet is allowed to emerge cleanly from the outlet with highpositional accuracy. Throated structure may correct for droplet anglesof up to about ±22.5°, but more accurate trajectory or correctionresults may be obtained when the droplet angles are between about 0°-15°off-axis.

[0045] To facilitate efficient gas or air flow through the throatedstructure, the throat is preferably surrounded by a wall having across-sectional elliptical shape. That is, the cross-sectional profileof the wall taken in a plane that is parallel to or includes the axis ofthe nozzle preferably follows a partial elliptical shape. The exitchannels which draw the gas or air away from the centerline of thethroat may also have elliptically shaped paths to help maintain smoothlaminar flow throughout the structure. It also helps to bring the gas orair flow parallel to the centerline as well as maintaining a smoothtransition for the exit flow as well as maintaining an equal exit flowon the throat diameter. This in turn may help to efficiently andeffectively eject droplets through the structure.

[0046] In addition to the throated structure, alternative variations ofthe device may include a variety of additional methods and/or componentsto aid in the gas/air flow or droplet steering. For instance, the nozzlemay be mounted or attached to a platform which is translatable in aplane independent from the well plate over which the nozzle is located.As the well plate translates from well to well and settles intoposition, the nozzle may be independently translated such that as thewell plate settles into position, the nozzle tracks the position of awell from which droplets are to be ejected and aligns itselfaccordingly. The nozzle may be tracked against the well plate andaligned by use of a tracking system such as an optical system, e.g., avideo camera or digital camera, which may track the wells by a trackingalgorithm on a computer.

[0047] Additionally, an electrically chargeable member, e.g., a pin, maybe positioned in apposition to the outlet to polarize the dropletsduring their travel towards the target. Polarizing the droplets helps toinfluence the droplet trajectory as the droplets are drawn towards thechargeable member for more accurate droplet deposition. Additionally,well inserts for controlling the ejection surface of the pool of sourceliquid from which the droplets are ejected may also be used inconjunction with the throated structure. Furthermore, various manifolddevices may be used to efficiently channel the gas or air through themechanism.

[c] X/Y Linear Stage Assemblies

[0048] The X/Y linear stages may be used to manipulate the sourcevessels and the target device above the acoustic emitter device. Thismay allow the liquid transfer apparatus to transport a liquid from anysource location to any target location. In one variation, the X/Y linearstages, along with the elevator storage queue, provide the mechanism toposition any well on any source vessel or target device above theacoustic emitter.

[0049] The X/Y linear stages may be sized accordingly to variousstroke/travel specifications, as one skilled in the art wouldappreciate. The X/Y stage may be designed to complement the storagequeues, the source vessels and/or the target device.

[0050] In one variation, the acoustic emitter device is in a fixedlocation, and with the assistance of the X/Y linear stage the sourcevessel and the target device are movable in the X/Y plane to selectivelyalign a source well on the source vessel with the target well on atarget device with the acoustic emitter. However, one skilled in the artwould appreciate that other variations are also possible. For example,the position of the target device may be fixed, and the source vesseland the acoustic emitter device are allowed to move in the X/Y plane.Alternatively, the source vessel may be in a fixed position and thetarget device and the acoustic emitter are given freedom of movement inthe X/Y plane. It is also within the contemplation of this inventionthat all three elements (the source vessel, the target device and theacoustic emitter) may move in the X/Y plan independent of each other.The X/Y plane movements may allow any source location to be aligned withany target location and the acoustic emitter. Only two of the threeelements need to move to allow this dynamic alignment to take place.

[0051] In another variation, mechanisms may be provided to allowvertical movement of the source vessel, the target device and/or theacoustic emitter. An actuator may be provided to physically move theacoustic emitter. However, mechanisms may also be provided for adjustingthe location of the focus for the acoustic beam without physicallymoving the position of the complete acoustic emitter unit.

[0052] The X/Y linear stage provides the mechanism to retrieve sourcevessels and target devices from their receptive storage queue andposition them over the acoustic emitter. Other mechanisms fortransferring objects (e.g. robotic arms) which can serve similar purposemay also be adapted in the liquid transfer apparatus. Although theobject transfer mechanism describe herein only has two-dimensionaldegrees of freedom, one skilled in the art would appreciate that theobject transfer mechanism may be modified to have additional degrees offreedom. For example, the linear stage may be adapted on an elevator toprovide motion in the Z direction.

[0053] In another variation, two X/Y linear stages are provided, one forhandling the source vessel and the other for handling the target device.The two linear stages may be arranged in a stacked configuration, onepositioned above the other. The linear stages may be located behind theacoustic emitter device. In another variation, the X/Y stages may bearrange opposite to one another, one on each side of the transporterdevice. In this configuration, the X/Y linear stage may be able totransport the well plates from the front of the system to the back ofthe system. The X/Y linear stages may be positioned in variousconfigurations, including implementing them as an interface with otherexternal devices to facilitate automation. For example, the X/Y linearstages may extend beyond the main compartment holding the acousticemitter, so that well plates may be retrieved from a separate storagesystem holding various well plates.

[0054] In addition to the two X/Y linear stages described above,additional X/Y linear stages may be added along with other transportassemblies such that multiple source and target well plates or substratemay be processed simultaneously. In one variation, separate sets of X/Ylinear stage assemblies may be implemented to retrieve well plates fromdifferent storage queues containing different sets of chemicallibraries. For example, the liquid transfer apparatus may be supportedby three sets of X/Y linear stages interacting with three sets ofelevator storage queues, each holding a different set of chemicallibrary. Alternatively, one main storage queue may support multipleliquid transfer apparatus. For example, one storage queue containing alarge chemical library may support three liquid transfer units thatsurround it. Each liquid transfer unit may have a X/Y linear stage thatextends to the main storage queue for retrieving source well platescontain the chemical library. In addition, each liquid transfer unit mayhave its own target storage queue for storing its own sets of targetwells, which may hold a predefined set of chemicals to be tested againstthe main chemical library. A system configured in this fashion may allowthree sets of chemicals to be tested against one primary chemicallibrary simultaneously. Various other configuration that are well knownto one skilled in the art may be implemented to design scalable systemsfor large scale, high throughput production lines for chemical synthesisand/or lead compound screening.

[d] Handling Device—Attached to the X/Y Stage Assembly

[0055] The handling device may be an integral part of the X/Y linearstage assembly or it may be separate mechanisms that may be easilydetached from the X/Y linear stage, depending on the design need of theoverall system as one skilled in the art would appreciate. For example,the handling device may be a gripper assembly that may be easilydetached from its X/Y linear stages. Single and/or dual axis mechanismmay be utilized to manipulate a wide variety of well plates, substrates(e.g. glass plate, glass slides, polymeric plate), or liquid containmentdevices for holding source liquids or serving as target devices.Automated grippers that are commonly used in the industry to move wellplates tend to lack precision repeatability in their ability to hold thewell plates within the grippers in the same position every time. Inapplications where the handling devices are used to hold and align wellplates in a precise manner, a device capable of holding and securingwell plates in a consistent manner may provide significant advantages.

[0056] In one variation, the system aligns (or calibrate the amount ofmisalignment with a reference axis defined by the system) the well plateeach time a well plate is picked up. This alignment process may beachieved through detecting and measuring two or more fiduciary points ona well plate to determine the amount of misalignment of the well plate.Base on this misalignment determination the system may then compensatewith appropriate amount of displacement when moving the well plate sospecific location, such as a well, may be lined up with a referencepoint on the system. With this approach, the system may also compensatefor variation in well plate size since each well plate is aligned eachtime it is picked up by a handling device. In another variation, thealignment of each handling device is aligned once when it picks up thefirst well plate. This variation may be feasible if al the well plateare the same size and variation between well plate is minimal relativeto the amount of precision of alignment required. In this approach, theability for the gripper assembly to hold the well plates in a repeatableand consistent manner may be important to overall system performance.

[0057] In another variation, the handling device may apply forces inthree separate axes such that an object held by the handling device maybe forced into the same corner (or wedge) in a consistent manner. Otherforce/pressure distribution systems well known to one skilled in the artmay also be implemented to ensure that when the same well plate is heldby the handling device the well plate is held at the same positionrelative to the gripping mechanisms of the handling device.

[0058] The handling device may also be designed in such a way thatpressure is applied to the object being held in the default position.Thus, in order for the controller to release the object (e.g. a wellplate) being held by the handling device, power or energy must bedelivered to active mechanisms (e.g. motor or piston) to force thegripping mechanism to release pressure on the object being held. Such adesign may prevent accidental dropping of well plate during powerfailure or emergency shutdown of the system.

[0059] The handling device may have removable/replaceable fingerattachments or extensions, which have costume shapes adapted to handle aparticular kind of well plate or fluid container. This design featuremay allow the system to be quickly customized to handle well plates ormicrotiter plates of various dimensions.

[e] Storage Queues

[0060] The storage queue may be a rack or other holding structures forstoring a plurality of well plates, liquid containment structures, ortarget devices. In one variation, the storage queue comprises of one ormore elevator assemblies. In each elevator assembly, there may bemultiple source vessels and/or target devices. In one variation, twoelevators are provided with one elevator storing all the source vesselsand the other stores all the target devices. The elevator may movevertically to position the appropriate source vessel or target devicefor retrieval by the handling device.

[0061] The source vessel and target device may be well plates that arecommonly used in the biotechnology industry. The source vessels andtarget device may also be any liquid containment structures, which iscapable of holding a plurality of isolated pools of liquids, well knownto one skilled in the art. The source vessels and target vessels mayalso be flat surfaces, which is capable of holding individual pools ofliquids on its surface. Chemical coatings, such as hydrophobic orhydrophilic materials, may be implemented to improve liquid isolation onor in the vessels. The source vessel and target device may comprise ofthe same material. For example both the source vessels and the targetdevices may be well plates. Alternatively, the source and target vesselsmay be different materials. For example, the source vessels may be wellplates and the target devices may be glass plates with coatings. It isalso within the contemplation of this invention that source vessels maycomprise of different liquid containment structures. For example, withinthe elevator holding the source vessels, some source vessels may be wellplates and some vessels may be glass plates. The target vessels may alsocomprise of different liquid containment structures. Barcode or othermarkers may be provide on the source vessels and/or the target device sothe liquid transfer system may track the well plates that are beinghandled by the system. By detecting the barcodes, the system may trackthe well plate in the storage queues. Sensors or other detectors may bepositioned within the liquid transfer apparatus to read the markers orbarcodes on the well plates and track the well plates while they arebeing handling by the liquid transfer system. The barcode or markers mayalso be used to track other source fluid containment structures or fluidreceiving surface or containment structures that are implemented in theliquid transfer apparatus.

[0062] The storage queues (e.g. elevators) may be sized accordingly tomeet various source vessel storage requirement. For example, theelevator may be sized to hold well plates of particularheight/width/depth. The storage queues may also have a built-inmechanism for adjusting the vessel holder or slot for securing wellplates of various sizes within the storage queues. Depending upon thetype of source vessels used, an entire library of biological compoundsmay be stored in the storage queues. For example, an elevator with tenslots, each slot holding a well plate with 1536 wells, may hold abiochemical library with 15360 compounds.

[0063] In another variation, the storage queue may be a device withfixed drop-off locations for individual well plates. In this design,individual well plates may be fed to the liquid transfer apparatus byplacing the well plate at the drop-off location. A transfer device, suchas a robotic arm or a mechanical gripper may transfer the well platefrom the drop off location to the fluid ejection location or the targetlocation on top of the acoustic emitter. Well plates may be loaded ontothe drop-off location by manual transfer or via robotic automation. Inanother variation, a separate storage/sorting device holding well platesmay interface with the liquid transfer apparatus through the drop-offlocation by feeding and retrieving well plates from the drop-offlocation.

[0064] In yet another variation, the storage queue may comprise ofrotating carousel type mechanisms. The carousel may provide rapidinterchange of well plates. For example, the carousel may hold 1 to 8,or more, well plates and may be loaded/unloaded manually or withautomation. In another design variation, the carousel may have multiplestack or levels. The carousel may also incorporate elevator mechanismsfor facilitating access of well plates within the various levels in thecarousel.

[0065] In one variation, when the storage queue are not being accessedby the gripper assembly, the storage queue may be lowered into a cavityor climate chamber, where environmental parameters (e.g., temperature,humidity) may be controlled. This climate chamber may also be filled awith specific gas to facilitate cell growth or initiate chemicalreactions. The chamber may also be heated to increase the rate ofchemical reactions taking place within the well plates.

[f] Image Detection System

[0066] The image detection system may comprise a vision system withvariable focus capability. For example, in one variation, the imagedetection system may focus on three separate planes (e.g., the planewhere the tip of the acoustic emitter is located, the plane where thesource vessel is positioned, and the plane where the target device islocated.). The image detection system may have various focal depthsdepending on the particular design need, as one skilled in the art wouldappreciate. In one variation, the image detection system may comprise ofa CCD camera, lenses for focusing images on the CCD and motorizedmechanisms for adjusting the focus. In another variation, the imagedetection system comprises a fixed-focus vision system. The fixedfocused system may be adjusted vertically by an actuator so that thefocus location of the camera may be adjusted by shifting the position ofthe camera/lens unit. Other electronic hardware and/or software may beimplemented to enhance image detection and/or provide automatic focusadjustments, as one skilled in the art would appreciate.

[0067] The image detection system may provide the input signal for thecontrol mechanism of the overall system to align the source vessels andthe target device. The image detection system may also be used tomonitor and verify the fluid transfer process. For example, the imagedetection system may be used for quality control. One of the limitationsin most of the gene array fabrication devices in the market is theinability to verify the quality of each printed DNA spot after it isprinted. The image detection system may allow the fluid transferapparatus disclosed herein to verify whether a drop of liquid wassuccessfully transfer on to the target device in real time. For thisapplication, the target device may comprise of transparent ortranslucent materials. Furthermore, the image detection system mayfurther allow size of the delivered droplet to be measured. The volumeof the liquid delivered may be calculated based on the diameter of thedroplet.

[0068] The image system may also be used to monitor post deliverychanges within the target device. For example, a well on the targetdevice may contain chemical compound A. A liquid containing chemicalcompound B may be ejected out of a well in the source vessel, into thewell on the target device which contain chemical compound A. Chemicalcompound A may react with chemical compound B and give off a fluorescentlight. This fluorescent light may be detected and measured by the imagedetection system. A computer may determine the chemical reaction base onthe color of the fluorescent or the intensity of the fluorescentdetected. Other chemical/biochemical reactions and associated method fordetecting and measuring the reactions, which are well known to oneskilled in the art, may also be implemented in this liquid transferapparatus.

[0069] Target device may also be pulled from the storage queue for thesole purpose of monitoring and/or tracking chemical reactions orbiological/biochemical indicators with the image detection system. Forexample, proteins placed in various wells in a target well plate may betreated with different chemicals from a chemical library by ejectingdifferent chemicals into each well on the target well plate. The targetwell plate may be incubated within the storage cue for a period of timebefore it is pulled from the storage queue and examined under imagedetection system.

[g] Machine Controls, Electronics and Software

[0070] A computer with associated electronics may be implemented toprovide overall control of the liquid transfer system. Variouscomputation device, processors, controller, etc., which are well knownto one skilled in the art, may be configured to provide processingcontrol to various components in the liquid transfer apparatus. Softwareand/or graphic user interface may also be implemented to provide controland/or monitoring functions to the system.

[0071] For example, system software may be programmed to defineselective amounts of liquid to be transferred in each individualejection. A graphic user interface may provide a user-friendlyenvironment where the user can easily enter the desired liquid amount tobe transferred in each ejection. When the program executes, it maycontrol the amount of acoustic wave energy and/or the location of thewave-guide focus of the acoustic emitter, thus defining the amount ofliquid being ejected.

[0072] The system controller may also be programmed by the user withinstructions defining where, when and/or what volume of liquid totransfer during each ejection. Specific sequence of liquid transferprotocol may be fed into the computer and executed by the liquidtransfer system. The user may also define the selective location ofsource liquid to be transferred into each well in the target wellplates, and allow the computer to determine the optimum sequence oftransfer. Because of the random-access liquid transfer capabilitydescribed above, the liquid transfer system described herein does nothave to transfer/eject fluid in a linear fashion (one well after anotheron the same row or column). Since the system may allow the user toselect any source location from any well plate in the storage queue, andtransfer it to any target location on any target well plate/substrate inthe storage queue, software may be provide to calculate the optimaltransfer sequence based on the pattern of the target well plate to becreated (the end product) and calculate the most efficient transfersequence.

[0073] Software may also be implement in the control system to allowefficient reformatting of well plate type (e.g., 384, 1536, etc.) to thesame or different type of plates. In one variation, four 384 type wellplates may be reformatted into one 1536 type well plate. For example, a1536 well plate man be divided into four (4) equal quadrants of 384wells. Liquids from each well of the 384 well plates would betransferred directly into a corresponding well of the target 1536 wellplate. For instance, well plate #1 may be transfer to quadrant #1 of the1536 target and keep all of the source wells in the same row/columnorder. In other words, take the four plates and combined them into one.In another variation, the liquids in the wells of well plate #1 may bescattered in any fashion to any 384 wells of the target 1536 plate. Thewells of plate #2 would go to any of the remaining 1,152 wells, and soon. Again, four plates go into one, but now they are not in an orderedsequence that corresponds to the sequences on the original 384 wellplates.

[0074] In addition, the system may also be implemented to reformat arraydensity. For example, liquid may be extracted from a 1536 well plate tocreate an array of liquid spots within a 1 square cm area thatcorresponds to the array in the 1536 well plate.

[0075] In yet another variation, the system may randomly select sourcewells in a non-sequential fashion and dispense them into an array oftarget locations in a sequential or non-sequential format. For example,it may be used for “cherry picking” source well liquids and dispensingthem in precise sequential locations within other assay well plates. Inanother example, it may be used for selecting source well liquids anddispensing them in precise sequential locations on porous or non-poroussubstrates.

[h] Database

[0076] In one aspect of the invention, a database is provided to manageuser inputs and or instruction sets for transferring liquid from anysource locations within a collection of source fluid containmentstructures to any target locations within a collection of targetdevices. “Database” as used herein means “a collection of data organizedespecially for search and retrieval by a computer.” The computer maycollect and store data in the database during real time operation of themachine to facilitate resource distribution tracking and/or for furtheranalysis. The database may contain information such as user definedliquid transfer map or sequence information, well plate IDs, well plateconfigurations, source liquid volumes, depth of liquids in each sourcewell, source liquid type, source liquid surface tension, source liquidviscosity, source liquid location on the well plate, age of sourceliquid (e.g., when it was created), how often the source liquid has beenaccessed, first/last time source liquid was accessed, time-stamp andother information related to each liquid ejection (e.g., volume or sizeof liquid droplet transferred, amount of acoustic energy used for thetransfer). Information in the database may be updated to track changesin the system. Furthermore, information may also be added to thedatabase as needed.

[0077] In one variation, each source library, which is comprised of aseries of well plates holding a library of chemicals or biochemical, hasa corresponding database file describing the content of each source, itslocation and corresponding volume and/or fluid height. The user mayprovide information defining specific locations on the target plates andcorresponding source liquid and the volume to be transferred onto eachtarget location. Base on the information in these databases, the liquidtransfer platform may generate a new liquid library on a series oftarget well plates (by selectively transferring liquids from the sourcewell plates to the target well plates), and an output databasecontaining corresponding information regarding liquids at each of thetarget locations (e.g., liquid source (identifying or destinationinformation) and/or volume of liquid at each location). The outputdatabase may be stored on a removable data storage medium (e.g. floppydisk, removable hard disk, miniature USB disk, compact flash card,memory stick, etc.) so it may be transferred to a remote facility alongwith the new liquid library. Alternatively, the output database may betransferred to the remote facility through a computer network.

[0078] In another variation, an input data set or mapping profile isprovided with information regarding specific source locations, volume ofliquid to transfer from each location and corresponding target locationwhere each defined volume of fluid is to be transferred. The data may beprovided on a memory device or transferred onto the liquid transferplatform through network connections. Base on the information provided,the liquid transfer platform generates a set of target plates with thedesired liquids in the predefined locations. An output databasecontaining information regarding the liquids on the target plates and/orinformation tracking the transfer process (e.g. time-stamp,successfulness of the transfer, volume transferred, and/or volumeremained in the source wells) may be provide for each set of outputtarget plates.

[0079] The ability to track the volume of liquids transferred out of thesource wells may allow the system to track the height of the liquid ineach source well and thus allow efficient positioning of acoustic wave'sfocus. Furthermore, tracking the remaining volume of the liquid in thesource wells as fluids are ejected from the source well may also allowmore efficient utilization of resources.

[0080] The data base may also be utilized to track alignment andassociated coordinate information. In addition, information regardingoptimal focus location(s) for the acoustic waves and/or fluid depth(fluid height, fluid surface location, fluid volume) in each of thesource fluid wells may also be maintained in the database. Theinformation maintained in the database may be used to speed the processof well plate alignments and facilitate the positioning of thewave-guide during each fluid ejection cycle.

[0081] The database may also be implemented to provide feedback and/orverification of the transferred liquids, which may also include volumeinformation. Error recovery algorithm or protocols may be implementedalong with the database to improve or manage the output liquid arrays'quality. For example, error recovery mechanisms may be applied to verifythe detection of source liquid level and/or droplet ejection. The errorrecovery mechanisms may implement necessary correction measures whenliquid level detection failed or when droplet ejection did not reach itsintended target.

[0082] As described earlier, the non-contact liquid transfer apparatusmay be configured to function with multiple database. For example, theapparatus may utilize a source library database and a mapping database,and generates an output library database. However, it is also possibleto configure the apparatus to retrieve and store all the informationfrom a single database.

[0083] In addition, when multiple liquid transfer apparatuses are beingoperated at the same time. All the liquid transfer apparatuses may belinked to a central computer with a centralized database through acomputer network. The network of liquid transfer apparatuses may beconfigured such that all the source and target information are managedby the central computer and information are passed to the localdatabase, which reside on the computer in each liquid transferapparatus, when it is needed. The local database on each apparatus maymaintain additional information that are unique to that particularapparatus (e.g., calibration information, operation or functionalparameters for the various mechanisms in the apparatus, data regardingspecific well plates that are being stored in the storage queues in thatparticular apparatus, etc.). The local computer operating on eachapparatus may also retrieve additional data from the central computer tofacilitate the operation of the liquid transfer apparatus.

[i] Frame and Support Structure

[0084] The frame and support structure may be provide for integratingthe liquid transfer apparatus and its related supporting devices intoone stand alone unit. Various mechanical sub units may be attached to aprimary frame so that the different moving parts may be aligned and/orcalibrated for precision interactions. Various compartments may beprovided within the frame and supporting structure for housingsupporting electronics and peripheral support devices. For example, acompartment may be provided for housing the system control computer. Aseparate compartment may house an environmental temperature controlunit. Another compartment may be provided for housing a carbon dioxidesupply source for supplying the primary enclosure or chamber with carbondioxide gas.

[j] Environment and Safety Enclosure

[0085] An enclosure or chamber may be provide to house the liquidtransfer apparatus. Various devices and mechanisms, which are well knownto one skilled in the art, may be implemented to control specificparameters within the enclosure. Some of the environmental factors thatmay be monitored and/or controlled include, but are not limited to,temperature, humidity, air pressure, air flow, air cleanliness, destinyof particles inside the chamber (e.g. air filtration), light exposurelevels (e.g., ambient light to complete black-out), lighting environment(e.g., constant UV light), and gas atmosphere compositions (nitrogen,argon, carbon dioxide, etc.). One or more of the above parameters may bemonitored and/or controlled at the same time.

[0086] The enclosure or chamber may also prevent unintended user accessduring system operation. The access doors to the enclosure may beautomatically locked, while various mechanisms in the liquid transferapparatus are moving to prevent accidental injury to users. This mayalso prevent the user from prematurely accessing the source vessels ortarget devices before the completion of a programmed fluid transferprotocol. Emergency shutdown interface (e.g., a button or valve) mayalso be provided for terminating system operation.

BRIEF DESCRIPTION OF THE DRAWING

[0087] In the accompanying drawings, reference characters refer to thesame parts throughout the different views. The drawings are intended forillustrating some of the principles of the wave-guide assembly and arenot intended to limit the description in any way. The drawings are notnecessarily to scale, emphasis instead being placed upon illustratingthe depicted principles in a clear manner.

[0088]FIG. 1A illustrates one variation of an high-throughputnon-contact liquid transfer apparatus with an integrated enclosure.

[0089]FIG. 1B illustrates an expanded view of the liquid transferprocessing area of the high-throughput non-contact liquid transferapparatus shown in FIG. 1A.

[0090]FIG. 2A illustrates one variation of a non-contact fluid transferapparatus.

[0091]FIG. 2B is a schematic diagram illustrating another variation ofthe non-contact fluid transfer apparatus, where an acoustic wavegenerated by a piezoelectric element is propagated though a wave guide,a coupling medium, and a source fluid containment structure to a pool ofsource fluid, causing ejection of a droplet of source fluid from thesurface of the pool.

[0092]FIG. 3A illustrates a cross sectional view of one variation of awave-guide assembly where the wave-guide is moveably deposed in theinner lumen of a fluid basin.

[0093]FIG. 3B is the top view of the wave-guide assembly shown in FIG.3A.

[0094]FIG. 4A illustrates one variation of the fluid basin thatsurrounds the wave-guide, where the outer wall is higher than the innerwall, which separates the suction channel and the coupling liquid supplychannel.

[0095]FIG. 4B illustrate another variation of the fluid basin where theouter wall is lower than the inner wall, which separates the suctionchannel and the coupling liquid supply channel.

[0096]FIG. 5 shows another variation of the wave-guide assembly wherethe wave-guide unit and the surrounding channels are octagonally shaped.

[0097]FIG. 6A shows another variation of the wave-guide assembly where acoupling liquid supply channel surrounds the wave-guide, and the vacuumsuction channel comprises a plurality of channels surrounding thecoupling liquid supply channel.

[0098]FIG. 6B shows yet another variation of the wave-guide assemblywhere both the coupling liquid supply channel and the vacuum suctionchannel are each comprised of two separate channels.

[0099]FIG. 7 shows another variation of the wave-guide assembly wherethe wave-guide and the fluid basin are connected to each other.

[0100]FIG. 8A shows one variation of an acoustic wave emitter modulewhere a wave-guide is integrated within a sealed housing along with, atransformer, a inductor, and other electrical and mechanical parts.

[0101]FIG. 8B shows the same acoustic wave emitter module of FIG. 8A ina disassembled condition for illustration purpose.

[0102]FIG. 9A illustrates a variation of a linear servomechanism forpositioning the acoustic wave emitter module along a vertical axis. Themechanism includes a fluid compensation system for adjusting the volumeof the coupling liquid at the distal end of the wave-guide to offset anychanges caused by the movement of the wave-guide.

[0103]FIG. 9B illustrates the same linear servomechanism of FIG. 9Awithout the acoustic wave emitter module.

[0104]FIG. 9C illustrates the frontal view of the linear servomechanismshown in FIG. 9A.

[0105]FIG. 10 illustrates one variation of an overall system layout forsupplying coupling liquid to the fluid basin.

[0106]FIG. 11A shows one particular design of a fluid basin, where thewave-guide positioned at the distal end of an acoustic wave emittermodule, shown in FIG. 8A, may extend into the inner lumen of the fluidbasin, which is designed to provide a negative pressure in the immediatearea surrounding the inner lumen that forms the coupling liquid inlet.

[0107]FIG. 11B illustrates one variation of a thrust bearing assemblyfor positioning the fluid basin of the wave-guide assembly. Thebearings, spring and washer, are shown in the dissembled condition forillustration purpose.

[0108]FIG. 12 shows a schematic diagram of variations of the method forutilizing a negative pressure to isolate a coupling liquid at the distalend of a wave-guide.

[0109]FIG. 13A shows a representative schematic diagram of a dropletsteering mechanism attached to a position adjustment assembly, which maybe integrated into a non-contact liquid transfer apparatus.

[0110]FIG. 13B shows a representative schematic diagram of a throatedstructure, which illustrates, in part, the general operation of thedroplet steering mechanism.

[0111]FIG. 13C shows an example of a droplet steering mechanism with awell plate and a target device.

[0112]FIG. 13D shows another variation of the droplet steering mechanismwith an electrically chargeable member positionable above the targetdevice.

[0113]FIG. 14 illustrates one variation of an X-Y linear stage.

[0114]FIG. 15A illustrates one variation of a gripper assembly holding awell plate.

[0115]FIG. 15B illustrates the same a gripper assembly of FIG. 15Awithout a well plate.

[0116]FIG. 15C illustrates the gripper assembly of FIG. 15A with its topcover opened showing various components within the gripper assembly.

[0117]FIG. 15D illustrates the gripper assembly of FIG. 15A with thewell plate up-gripped.

[0118]FIG. 15E illustrate one variation of an “finger” that may beattached to a gripper assembly to assist the gripper assembly tosecurely grip a well plate.

[0119]FIG. 15F illustrates the gripper assembly of FIG. 15A interactingwith an elevator storage queue.

[0120]FIG. 15G illustrates the gripper assembly of FIG. 15A inter actingwith an elevator assembly by gripping a well plate located within a sloton an elevator storage queue.

[0121]FIG. 15H is a bottom view of one combination of gripper assemblyand elevator assembly, illustrating the elevator/gripper clearance. Thegripper is shown in an un-gripped or expanded position.

[0122]FIG. 16 illustrates one variation of an elevator storage queue.

[0123]FIG. 17A illustrates one variation of an image detection system.

[0124]FIG. 17B illustrates the imaging detector capturing reflected froma spherical fiducial mark that are parallel to the image system axis.

[0125]FIG. 17C illustrates one variation of a fiducial mark formed witha reflective sphere embedded in a well plate.

[0126]FIG. 17D is a plan view of a spherical fiducial mark.

[0127]FIG. 18A shows one variation of a control systems block diagram.

[0128]FIG. 18B shows one variation of a software block diagram.

[0129]FIG. 19 shows one variation of a database management system blockdiagram.

[0130]FIG. 20 illustrates one variation of a skeleton-like frameworkwith corresponding panels.

DESCRIPTION OF THE INVENTION

[0131] Before describing the present invention, it is to be understoodthat unless otherwise indicated this invention is not limited tospecific type of well plate, acoustic emitter, image detection system,or the like, as such may vary.

[0132] Liquid transfer is used herein as an example application toillustrate the functionality of the different aspects of the inventiondisclosed herein. It will be understood that embodiments of the presentinvention may be applied in a variety of processes and are not limitedto providing liquid transfer. For example, variations of the presentinvention may be adapted for high throughput chemical synthesis or forscreening lead compounds in a pharmaceutical discovery process. It willalso be understood that embodiments of the present invention may beapplied for ejecting various fluids, liquids, mixtures of liquids,liquid/compound mixture, biochemical, proteins, cells, etc., intovarious medium or space, and it is not limited to applications fordistribution of liquids into a well plate.

[0133] Well plates are used in various examples herein to illustrate thefunctionality of different aspects of the innovation disclosed herein.It will be understood that embodiments of the present invention may beimplemented with various other fluid containment structures, fluidreceiving structures, vessels, porous surfaces, non porous surfaces,etc., and are not limited to well plates.

[0134] Acoustic wave is used herein to include all acoustic waves whichare well known to one skilled in the art, whether they are continuous orintermittent waves. Various simple waveforms, complex waveforms, andwave-pulse are within the contemplation of this invention. Acoustic waveas used herein also includes a wave propagating as a result ofconcentration of energy in the vicinity of the surface of apiezoelectric substrate. The acoustic wave implemented in this inventionis preferably has a frequency between 100 kHz and 1 GHz; morepreferably, between 0.5 MHz and 200 MHz; and most preferably between 15MHz to 50 MHz. The wavelength or frequency is preferably one that allowsa droplet of about 10 micro-liter or less to be ejected from a pool ofliquid.

[0135] It must also be noted that, as used in this specification and theappended claims, the singular forms “a,” “an” and “the” include pluralreferents unless the context clearly dictates otherwise. Thus, forexample, the term “a handling device” is intended to mean a singlehandling device or a combination of handling devices, “a chemicalcompound” is intended to mean one or more chemical compound, or amixture there of.

[0136] To aid in understanding the invention, one variation of a liquidtransfer apparatus is first described, followed by description ofdetails on various components within the liquid transfer apparatus.

The System Platform

[0137] Referring to FIG. 1A, one particular design variation of a liquidtransfer apparatus is shown. The primary liquid transfer mechanisms arehoused within an enclosure 1. A user interface comprised of a keyboard 3and a LCD monitor 5 is provided on the side of the enclosure. In thisvariation, other supporting electronics and mechanisms (e.g., computersystem, power supply, etc.) are also housed within in the overallenclosure. The liquid transfer device is located within the mainchamber. FIG. 1B is a close-up view showing some of the mechanisms inmore detail. An acoustic emitter device 7 is positioned below floor ofthe main chamber (or processing deck) with the distal end protrudingabove the floor of the main chamber or processing area. A storage queue11 comprise of an elevator assembly is provide on the left side of theacoustic emitter device for holding source liquid well plates. Thesource well plates are positioned within the elevator assembly withtheir well openings facing up, and contain source liquid to betransferred. A second storage queue 13, also comprise of an elevatorassembly is provide on the right side of the acoustic emitter device forholding target well plates. The target well plates are positioned withinthe elevator assembly with their well openings facing down and maycontain liquids or other compounds. Two X/Y linear stage assemblies 15,17 positioned behind the main chamber have arms extending in to the mainchamber. On the distal end of each arm is a handling device 19 securedto the arm. The two X/Y linear stages are stack one above the other. TheX/Y linear stages allow their corresponding handling device to move onan X/Y plane. The handling device, comprise of a gripper assembly, hasclamps that can open up and grip on to well plates in the storagequeues. The lower X/Y linear stage 15 and its handling device is primaryresponsible for retrieving source liquid well plates and positioningthem above the acoustic emitter device. The upper X/Y linear stage 17and its handling device is responsible for retrieving target well platesand positioning them above the acoustic emitter device and the sourceliquid well plate. Because the elevator system 11, 13 provides verticalmovement to the stack of well plates in the queue, the handling devicemay retrieve any of the well plates within the elevator queue. An imagedetection system 21 comprised of a vision system is positioned above theacoustic emitter system 7 and secured to a frame on the back of the mainchamber. The image detection system 21 is aligned with the acousticemitter device 7. A computer controller, along with its associatedelectronic and software, provides overall control of the complete unit.The main chamber is within an environmental and safety enclosure 1.

[0138] For illustration purpose, one variation of a liquid transfersequence is described below. Under the control of a computer (not shown)the source elevator assembly position the desired source well plate atthe level accessible by the lower gripper assembly. The lower X/Y linearstage positions its gripper assembly around the source well plate. Thegripper assembly locks on to the source well plate and transfer thesource well plate to the top of the acoustic emitter device. The imagesystem detects the presence of the source well plate. The image system,along with multiple fiduciary markers on the well plate, allows thecomputer controller to calculate the position of the well plate and makeany necessary alignment adjustment. Following a similar procedure, theupper X/Y linear stage retrieves a target well plate from the targetelevator assembly and makes alignment adjustments. Once the position ofthe well plates are calibrated, the computer controller can align aspecific well in the source well plate and a specific well on the targetwell plate on the vertical axis defined by the acoustic emitter. Anacoustic wave is then propagated into the pool of liquid in the sourcewell plate, forcing a drop of liquid to eject out of the pool and intothe well on the target well plate that is aligned above it. If thetarget well plate is transparent or translucent the vision system maymonitor the ejection process and verify that liquid has beensuccessfully transferred. After the completion of the ejection, thecomputer controller can realign a different set of wells for the nextejection. Because the computer controller may access any of the wells inthe source storage queue and any of the wells in the target storagequeue, the selection of the second set of wells for fluid transfer maybe completely independent of what was selected during the firstejection.

Acoustic Ejection

[0139] To aid in understanding the invention, the basic functionality ofan acoustic ejection system is described below. An exemplary acousticliquid ejection system 2, which incorporates a wave-guide 4, is shown inFIG. 2A. This particular variation of a non-contact liquid transferapparatus has one acoustic wave emitter 6 in electrical communicationwith a computer 8. During operation the acoustic wave emitter 6generates an acoustic wave that is propagated through a wave-guide 4.The acoustic wave may then be focused by a lens 26 prior to propagatingthrough a coupling liquid 12. The acoustic wave is propagated throughthe coupling liquid after which the wave is transmitted through a sourcefluid containment structure 10 where the wave enters a pool of sourcefluid 14 thereby causing ejection of a droplet, mist or stream of sourcefluid from the surface of the pool. A target 11 may be positioned abovethe source fluid containment structure to capture the ejected liquid.The source fluid containment structure 10 may be held on a movable stage16. The movable stage may reposition the source containment structure inthe horizontal X/Y directions and/or the vertical Z. The moveable stagemay be in communication with the computer 8, which allows the computerto select specific well on the fluid containment structure for ejectionby aligning the selected well on top of the wave-guide. The target 11may also be connected to a moveable stage, which may also be controlledby the computer to select specific location on the target for receivingthe ejected liquid. This arrangement may allow the user to selectivelyeject liquids out of a plurality of wells on the fluid containmentstructure one after the other, and at the same time selectivelyprescribe specific location on the target to receive liquid from eachejection. The wave-guide may also be coupled to an actuator such thatthe user may adjust the focus location of the acoustic wave, to positionit in the vertical direction within, above, or below the surface of thesource fluid as desired. The computer may have implemented thereinvarious algorithms to adjust the energy and/or the focal length of theacoustic wave emitter unit, as well as control and manage the focuslocation of the acoustic wave relative to a surface of a particular poolof source fluid present in or on a source fluid containment structure.

[0140] A similar system is described in U.S. application Ser. No.09/735,709 filed Dec. 12, 2000 entitled “Acoustically Mediated FluidTransfer Methods And Uses Thereof,” hereby incorporated by reference inits entirety.

[0141] Various aspects of the exemplary system will now be described inmore detail. Referring to FIG. 1, the system 2 includes at least oneacoustic wave emitter 6 in electrical communication with a computer 8.The computer 8 may be a stand alone computing machine, a dedicatedelectronic control box with its own processor, or an electronicprocessing unit integrated with the fluid ejection system 2. Forinstance, the computer may be a control card integrated within the fluidejection system. The computer 8 may provide feedback control of theacoustic wave emitter, the positioning of the wave-guide 4, and themoveable stage holding the source fluid container 10 to achievesynchronization and efficient fluid ejection. During operation, theacoustic wave emitter 6 generates an acoustic wave, beam, or pulse thatmay be propagated through a wave-guide 4. The acoustic wave may befocused by a lens 26 prior to propagating through coupling medium 12(e.g. coupling liquid) to focus the energy of the acoustic wave intoliquid 14 within a well of a microtiter plate. The acoustic wave ispropagated through a coupling medium 12 after which the wave istransmitted through source fluid containment structure 10 where the wavemay come into focus in a pool of source fluid 14 thereby causing aportion of the liquid to be ejected as a droplet, mist, or fountain ofliquid. In one variation, 20 MHz acoustic waves are generated by theacoustic ejection system. In another variation, 40 MHz acoustic wavesare implemented. Depending on the particular acoustic wave emitterimplemented in the system, the acoustic wave emitter may be able togenerate acoustic waves in a plurality of frequencies. The computer mayalso be used to control the specific frequency of acoustic wave beinggenerated by the acoustic ejection system.

[0142] Examples of source liquid containment structures 10 include, butare not limited to, single and multi-well plates commonly used inmolecular biology applications, capillaries (e.g., capillary arrays), aflat plate with isolated regions of fluids, and the like. However, othercontainers or structures may also be used to hold a liquid to beejected. Notably, the source fluid containment structure 10 may bedetachably affixed to a movable stage 16. The movable stage 16 may becontrolled by actuator mechanism 18 which contains a horizontal actuator20 or a vertical actuator 22 or a combination of the two actuators tocontrol the movement of the stage 16 in both the vertical and horizontaldirections. One or more horizontal actuator may also be implemented toallow the movable sate to move in both X and Y direction. The target 11may also be attached to a movable stage and able to move in the X/Ydirection and/or the Z direction. The actuator 18 may be incommunication with a computer 8 which controls the movement of the stageto select a source fluid 14 or to adjust focusing of the acoustic waveor beam upon the source fluid 14.

[0143] The computer 8 may have implemented therein various algorithms toadjust the focal length and energy of the acoustic wave emitter as wellas control and manage the location of the acoustic wave emitter relativeto a particular source fluid present in or on a source fluid containmentstructure. The position of the focus, relative to the surface of thesource fluid, may be adjusted by changing the position of the sourcefluid container and/or by adjusting the vertical height of thewave-guide/emitter unit. Accordingly, the system may be used to provideacoustic stimuli to optimally eject a droplet of the source liquid.[0144] The acoustic waves may be channeled from the acoustic waveemitter 6 (e.g., piezoelectric element) to the source fluid 14 via anacoustic wave channel or a wave-guide 4. Reference is made to FIG. 2Bwhich shows an acoustic wave 24 being generated by a piezoelectricelement 6 and propagated through acoustic wave channel (e.g., awave-guide) 4. The rapid oscillation of the piezoelectric element 6generates an acoustic wave 24, which propagates through the acousticwave-guide 4 until it strikes the focusing lens 26. The wave thenemerges into a coupling medium 12 (e.g., the coupling liquid) having alower acoustic velocity. The spherical shape of the lens 26 imparts afocusing effect on the acoustic waves, thereby focusing the acousticenergy into the liquid 14. The acoustic wave-guide 4 may be constructedof aluminum, silicon, silicon nitride, silicon carbide, sapphire, fusedquartz, certain glasses, or the like. In one variation, the acousticwave-guide 4 is constructed of aluminum. Suitable materials for thefabrication of the acoustic wave-guide may have an acoustic velocitythat is higher than the acoustic velocity of the source fluid. Thepiezoelectric element 6 may be deposited on, or otherwise intimatelymechanically coupled to a surface of the acoustic wave-guide 4.

[0144] In one particular design, a liquid transition interface isprovided to facilitate the propagation of an acoustic wave or beam fromthe wave-guide to a source fluid containment structure. The focusinglens may be implemented to direct the acoustic beam into an essentiallydiffraction limited focus within the source fluid pool. The focus may beplaced at or near the fluid/air interface at the surface of the sourcefluid pool.

[0145] One or more heat exchangers, heaters and/or coolers may also beprovided to adjust or maintain the coupling liquid at a desirabletemperature. Controlling the temperature of the coupling medium mayminimize any effect of temperature on the source fluid.

[0146] The coupling medium may have an acoustic impedance that is closeto the acoustic impedance of the source fluid containment structure. Thecoupling medium may be in contact with the wave-guide 4 and the bottomsurface of the fluid containment structure 10, thereby providing forefficient energy transfer from the acoustic wave-guide 4 to the fluidcontainment structure 10, and subsequently through the source fluid 14.In another variation, the acoustic wave emitter is directly coupled tothe source fluid containment structure 10 through the coupling medium12. As an example, a polystyrene multi-well plate has an acousticimpedance of about 2.3. Water has an acoustic impedance of about 1.7.Accordingly, water may be a good coupling medium when the source fluidcontainment structure is a polystyrene device (e.g., a multi-well plate)due the close match in impedance values between water and the plate. Byadding other fluids (e.g., glycerol, or the like) to the water, an evencloser match may be achieved. Other fluids may also be employed in thepractice of the present invention.

[0147] Thus, by providing a coupling medium 12 between the acoustic waveemitter 6, or preferably the acoustic wave-guide 4, and the fluidcontainment structure 10, an efficient transfer of energy may beachieved.

[0148] The acoustic wave emitter 6 may be any of various acoustic wavegenerators that are well known to one skilled in the art. In onevariation, a piezoelectric transducer is employed as an acoustic waveemitter 6. The piezoelectric transducer may comprise a flat thinpiezoelectric element, which is constructed between a pair of thin filmelectrode plates. As is understood by those of skilled in the art, whena high frequency and appropriate magnitude voltage is applied across thethin film electrode plates of a piezoelectric transducer, radiofrequency energy will cause the piezoelectric element to be excited intoa thickness mode oscillation. The resultant oscillation of thepiezoelectric element may generate a slightly diverging acoustic beam ofacoustic waves. By directing the wave or beam onto an appropriate lens26 having a defined radius of curvature (e.g., a spherical lens, or thelike), the acoustic beam can be brought to focus at a desired point.Acoustic energy may be modulated to deliver energy for a short period oftime or in short pulses to form an energy wave.

[0149] The piezoelectric transducer may have various forms including aflat crystal disk, or other crystal designs, e.g., square, perforateddisk, and the like. In one variation, the piezoelectric transducer maybe a flat disk. Because many electronic circuits are designed for a 50 Ω(ohm) load, it may be desirable to employ a 50 Ω transducer. Variouspiezoelectric materials, which are well known to one skilled in the art,may be suitable for fabricating the piezoelectric transducer. Examplesof materials which may be suitable for making the piezoelectrictransducer include Lithium Niobate, Lead Niobate and Quartz. Variousshapes of piezoelectric crystals are also contemplated for use in theimplementation of the present invention.

[0150] A computer may send an analog voltage pulse to the piezoelectrictransducer by an electrical wire. The voltage pulse may be controlled,for example, by a MD-E-201 Drive Electronics manufactured by Microdrop,GmbH, Muhlenweg 143, D-22844 Norderstedt, Germany. The electronics maycontrol the magnitude and duration of the analog voltage pulses, andalso the frequency at which the pulses are sent to the piezoelectrictransducer. Each voltage pulse may cause the generation of an acousticwave from the piezoelectric transducer, which in turn is propagatedthrough a coupling medium and into or through the source fluid therebyimpinging on the surface of the source fluid. Such acoustic waves may begenerated to eject a droplet, mist or stream, from the source fluid intoan excited oscillating state.

[a] Acoustic Emitter Device

[0151] Referring to FIG. 3A, one variation of a wave-guide assembly forisolating a liquid coupling medium at the tip of wave-guide 4 is shown.In this variation the fluid basin surrounding the wave-guide 4 comprisesa structure with two coaxial lumens, formed by an inner wall 42, and anouter wall 44, as shown in FIG. 3B. The inner lumen 32 forms a containerfor supplying coupling liquid to the distal end of the wave-guide. Awave-guide 4 may be positioned within the inner lumen 32 such that thewave-guide may be moved relative to the inner wall 42. The outer lumen34 formed between the inner wall and the outer wall may be a channel forapplying a negative pressure near the wave-guide 4 at the distal end 36of the assembly. The inner lumen 32 is the channel for providingcoupling liquid to the distal end 36 of the wave-guide 4.

[0152] A port 38 may be provided for accessing the outer lumen, as seenin FIG. 3A. A negative pressure generator may be connected to this port38 to generate a negative pressure area at the distal end of the outerlumen 34. The negative pressure generator may be connected directly tothe port, or alternatively, the negative pressure generator may beconnected to the port through tubing or other connectors or channels,which are able to provide a path from the port to the vacuum generator.The negative pressure generator may provide constant suction at thedistal end of the wave-guide assembly. Alternatively, the negativepressure generator may provide suction intermittently or on an as neededbasis.

[0153] A second port 40 may be provided for accessing the inner lumen32. A fluid source may be connected to the second port 40 to provide thecoupling liquid to the inner lumen 32. The fluid source may be connectedto the second port 40 through tubing or other connectors or channels,which are able to provide a path from the port to the vacuum generator.Additional ports may be provided for accessing the inner and/or theouter lumen.

[0154] In one variation, a fluid pump is connected to the second port40. The pump may also be connected to a fluid source or reservoir. Thepump may provide continuous flow of fluid into the inner lumen 32 of theassembly. Alternatively, the pump may provide fluid intermittently or onan as needed basis.

[0155] In another variation, shown in FIG. 10, the inner lumen 32 isconnected to a peristaltic pump 102, which is further connected to afluid supply bottle 104. The peristaltic pump draws coupling liquid 108from the fluid supply bottle 104 and pumps the coupling liquid into theinner lumen 32. A vacuum generator 106 is connected to the fluid supplybottle 104 for generating a negative pressure inside the bottle. Theouter lumen 34 is connected to the fluid supply bottle 104, and due tothe negative pressure inside the fluid supply bottle 104, couplingliquid is drawn from the outer lumen into the bottle 104. Thisparticular configuration allows the coupling liquid to flow from thefluid supply bottle 104 into the inner lumen, and exit at the outletsurrounding the wave-guide. Excess coupling liquid at the distal end ofthe wave-guide is drawn into the outer lumen and flows back into thefluid supply bottle 104.

[0156] In one variation of the invention, the pump supplies a constantflow of coupling liquid to the end of the wave-guide through the innerlumen and suction in the outer lumen constantly draws liquid away. Therate at which the coupling liquid is supplied to the end of thewave-guide and the rate of removal of coupling liquid by the suction maybe about the same, so that coupling liquid is supplied to maintain a“bubble” of liquid of constant volume at the end of the wave-guide.

[0157] In yet another variation, a computer may modulate the amount ofcoupling liquid supplied to the inner lumen 32 and/or the amount ofsuction applied to remove excess fluid, in order to control the amountsof fluids at the distal end of the wave-guide.

[0158] In one variation of the fluid basin 30 which surrounds thewave-guide 4, the inner wall 42, which defines the inner lumen and theouter lumen, is at the same level as the outer wall 44 of the assembly,as shown in FIG. 3A. In an alternative design, the inner wall 42 islower than the outer wall 44, as shown in FIG. 4A. In another variation,the inner wall 42 is higher than the outer wall 44, as shown in FIG. 4B.

[0159] The channel providing the coupling liquid and the channelsupplying the suction may surround the wave-guide cylindrically.Alternatively, the channels and supporting walls may form triangularshapes, rectangular shapes, pentagonal shapes, or other shapes that oneskilled in the art would consider suitable for the mechanical functionof the structure. The wave-guide 4 itself may also be adapted to othercross-sectional shapes that are functionally feasible. The shape of thewave-guide 4 may match the shape of the surrounding structure. However,this is not a necessary requirement. FIG. 5 illustrates one variation ofthe wave-guide assembly where an octagonal shape has been adapted.

[0160] The coupling liquid supply path 46 and the suction path 48 mayeach be comprised of individual channels. However, other combinationsare also possible. Both the coupling liquid path 46 and the suction path48 may be comprised of a plurality of channels or paths. The channelsmay have a cylindrical shape, but this is not required. For example, thechannels may have a triangular cross section. In FIG. 6A, one variationof the fluid/air channels is illustrated, where the fluid channel 46 iscomprised of a single cylindrical channel surrounding the wave-guide 4,and the suction channel 48 is comprised of a plurality of channelssurrounding the fluid channel 46. The suction channels 48 may beconnected to a single negative pressure source or a plurality ofnegative pressure sources. In another variation, both the couplingliquid supply channels 46 and the suction channels 48 are comprised ofdual channels positioned around the wave-guide 4, as seen in FIG. 6B.

[0161] In another variation, the wave-guide 4 may be connected to thefluid basin 30 surrounding the wave-guide, forming an integrated unit,as seen in FIG. 7. An optional suction channel (not shown) may surroundthe fluid channel 46 for removing excess coupling liquid. The integratedwave-guide/fluid basin unit may be coupled to a displacement device(e.g., an actuator), and may move in the vertical direction as acomplete unit.

[0162] In another aspect of the invention, the wave-guide and its fluidbasin may be integrated with a high-speed linear servo axis mechanism.In one variation, the device is designed to move the focus of thewave-guide to a desired position within a 12 mm vertical range within 50milliseconds, and appropriate compensation mechanisms as describedherein are provided to maintain the fluid coupling between thewave-guide 4 and the source fluid containment structure 10. Thewave-guide 4 may comprise an acoustic wave-conducting medium with a lensadapted at the distal end for focusing the acoustic wave. The fluidejection system may have additional constraints such that the linearaxis of the wave-guide unit is to maintain a 0.02 mm centerline acrossthe full stroke of the 12 mm displacement.

[0163] In one variation, the wave-guide 4 may be integrated within ahousing 50 as shown in FIG. 8A. The housing 50 may be part of a sealedunit, which forms the acoustic wave emitter module 52. FIG. 8B shows theacoustic wave emitter module in a disassembled condition. The acousticwave emitter module 52 comprises a wave-guide 4, a piezo-electrictransducer 51, connection wiring 53, location brackets 63 and screws 64,a transformer 54, an inductor 56, a sub-miniature electric connector 57,mounting screws 67 and covers 68, a data storage chip, and a base cover55. The transformer and the inductor may be utilized to provideimpedance matching between the acoustic wave emitter module and theinput power supply or the electric signal source supplying the currentto the piezo-electric transducer. The acoustic wave emitter module 52may be adapted to move on a vertical path as a unit. The movement of theacoustic emitter module 52 may be driven by a linear servomechanismcomprising a stage 58 coupled to a voice coil motor located within ahousing 59, as illustrated in FIG. 9A. The mechanical parts within FIG.9A is shown without tubing connecting the various ports 39 on fluidbasin 30 and the flow lines 74 to illustrate the main components of thesystem in a clear manner. The wave-guide housing 50 extends into a fluidbasin 30, and moves in the vertical direction within the basin 30. Thefluid basin 30 is positioned by a frame 61. The frame is couple to asupport panel 62. The voice coil motor may comprise fixed coils andmoving magnets located inside of the housing 59. Furthermore, a 0.5micron resolution linear encoder, a positive limit sensor, and a homesensor may also be built into a linear glass scale 66, which isconnected to the stage 58, to complete the closed loop system forcontrolling the position of the wave-guide 4, as seen in FIG. 9B. Thehome sensor refers to a sensor use to detect a reference location forthe moveable device.

[0164] In another aspect of the invention, a fluid compensation systemmay be provided to prevent pressure build up in the fluid basin 30 andmaintain adequate fluid coupling between the wave-guide 4 and the sourcefluid containment structure. In one variation, illustrated in FIG. 9C,the fluid compensation system comprises a built-in piston pump 70, andflow lines 74 to the fluid basin 30. The piston pump is comprised of apiston 75 acting upon liquid in a chamber 73 formed as part of thehousing 59. The voice coil motor may actuate a piston 75, which extendsinto a piston chamber 73 to displaces fluids from the piston chamber 73as the piston is forced downward by the voice coil motor 77, asillustrated in FIG. 10. The displaced fluid is force into the flow lines74, which are connected to the piston chamber 73. The flow lines directthe flow of fluid to the fluid basin 30. Thus, as the wave-guide islowered, coupling liquid displaced by the piston may compensate for theextra volume on top of the wave-guide due to the displacement. As thewave-guide is raised, the piston also rises to draw coupling liquid outof the basin via the flow line 74. The flow lines 74 may be sized totransfer a set volume of fluid with minimal pressure. The designminimizes pressure build up in the fluid basin 30 and minimizes ejectionof fluid from the basin during the quick linear movement of thewave-guide 4.

[0165] The distal end of the wave-guide unit described above may extendinto a fluid basin 30, which is shown in detail in FIG. 11A. In thisvariation, the fluid basin 30 has a fluid port for supplying fluids tothe inner lumen 83 surrounding the wave-guide. An air port is providedfor connection to a vacuum source for generating negative pressure inthe outer lumen 85. A trough 86 is provided for capturing excess liquidsthat spill over or splatter outside the suction area. A drain or channelmay be provided to remove fluids captured by the trough. The drain maybe connected to a negative pressure source to assist the removal offluids.

[0166] In yet another aspect of the invention, locking mechanisms areprovided to secure the fluid basin 30 in such a way as not to bias thecenterline of the wave-guide 4. A frame 61 may be provided to secure thefluid basin 30 and prevent movement of the fluid basin 30 in thevertical axis (Z-axis) direction. The frame 61 may be positioned with anindependent stage or it may be attached to another structure or stage inthe fluid ejection system. In one variation, shown in FIG. 11B, a thrustbearing assembly comprises of thrust bearings 92, a bearing cup 94, apreloaded spring 96, a washer 98, and a snap ring 100, is provide tosecure the fluid basin 30 on the frame 61 such that the fluid basin 30may have some degree of freedom in the X-Y plane (e.g., 1 mm X and 1 mmin the Y axis movement) but at the same time prevent any Z-axis movementof the basin. The freedom of movement in the X-Y plane minimizes sideloads that could be imparted to the wave-guide by the fluid basin due tomisalignment between the fluid basin and the wave-guide, and this mayprevent bias of the wave-guide centerline.

[0167] As shown in FIG. 9A, the frame 61 supporting the fluid basin 30may be couple to the support panel 62 of the system. In one variation,the frame 61 is attached to a carriage system, which is connected to thesupport panel 62. Linear motor may be incorporated to move the frame 61in the vertical directions and consequently moving the fluid basin 30,which surrounds the wave-guide. The linear motor may be controlled bythe system computer, thus allowing the vertical position of the fluidbasin 30 be adjusted as needed. For example, the vertical height of thefluid basin may be adjusted to control the amount of coupling liquid atthe distal end of the wave-guide.

[0168] In addition, the wave-guide and the fluid basin may be raised orlower concurrently so that appropriate space is maintained between thetip of the wave-guide and the bottom of the source fluid container thatis positioned above the wave-guide. The fluid basin may be loweredduring operation of the system to provide sufficient clearance above theacoustic wave emitter module for placement of source fluid container.

[0169] In this variation, the vertical position of the wave-guide andthe fluid basin may be adjusted independently. For example, well plateswith a skirt or edges that extends downward may be used along with theliquid ejection apparatus described herein. In order for the well platehandler to position the well plate above the acoustic emitter withoutbeing block by the distal ends of the wave-guide or the distal end ofthe fluid basin, it may be necessary to lower the wave-guide and thefluid basin in the vertical direction to provide sufficient clearancefor the skirt or the extended edges of the well plate. Once the sourcewell plate is in-place, the fluid basin and the wave-guide may then beraised.

[0170] Other coupling mechanisms and linear displacement devices ormotors may also be implemented to provide vertical displacement of theframe and the fluid basin that is coupled to the frame. In analternative design, linear displacement mechanisms are connecteddirectly to the fluid basin to allow the fluid basin to move on theZ-axis of the system.

[0171] In another aspect of the invention, detection of the fluid level(volume and/or height) of source fluid in the source fluid containmentstructure may be performed by observing the acoustic reflectionproperties of the pool of source fluid. For example, by detecting thereflection of the acoustic beam employed to eject the droplet from thesurface, the volume can be computed based on empirically determinedacoustic reflection characteristics. Since the acoustic wave emitter(e.g., a piezoelectric transducer) design may be similar to acousticmeasuring devices the droplet generator's transducer may also be usedfor acoustic depth sensing as a means of pool level or volume feedbackmeasurement. The signal may be processed and the system may then beadjusted to further move the focus of the acoustic wave or beam as thelevel or volume changes. Alternatively, the system may send a weakeracoustic wave, which does not cause fluid ejection, for the sole purposeof measuring fluid level. In another variation, a secondarypiezoelectric transducer can be employed to generate and/or detect theacoustic wave employed to detect the fluid level. The secondarypiezoelectric transducer may be toroidal and disposed around theperimeter of the piezoelectric transducer used to eject the droplet offluid (i.e., the primary transducer).

[0172] This invention further includes various methods of utilizingnegative pressure areas to isolate coupling liquid on a wave-guide. Inone variation, a wave-guide is provided for directing an acoustic wave.The wave-guide may be surrounded by a fluid channel for supplying acoupling liquid. The fluid channel may further be surrounded by an outerchannel for applying negative pressure. Coupling liquid may be directedto the distal end of the wave-guide followed by the generation of anegative pressure around the distal end of the wave-guide. The negativepressure area may remove any excess coupling liquid around the distalend of the wave-guide. A well plate may then be positioned above thedistal end of the wave-guide. The coupling liquid at the distal end ofthe wave-guide may come into contact with both the wave-guide and thebottom surface of the well plate. The well plate may be aligned with thewave-guide such that the well containing the desired source fluid isdirectly above the wave-guide. The position of the wave-guide may thenbe adjusted so that the focus of the wave-guide output is at a positionthat provides good ejection of droplets, mist or streams. An acousticwave with sufficient intensity and strength is then generated andpropagates through the wave-guide, the coupling liquid, and the sourcefluid containment structure, into the source fluid and forcing a drop offluid to eject from the surface of the source fluid pool. Othervariations of the method are illustrated in the schematic block diagramof FIG. 12.

[0173] In another variation of the method, a liquid is supplied to adistal end of a wave-guide and a constant negative pressure is providedin the area surrounding the distal end of said wave-guide. Excess liquidis captured and removed by said negative pressure. This variation mayfurther include providing a fluid containment structure having a bottomsurface and position the fluid containment structure on top of thewave-guide so that the liquid at the distal end of the wave-guide comesinto contact with the bottom surface of said fluid containmentstructure.

[0174] In another variation, coupling liquid is constantly supplied tothe end of the wave-guide. As the wave-guide is move vertically, thevolume of coupling fluid on top of the wave-guide is adjusted tocompensate for change in overall volume between the wave-guide and thesource fluid containment structure.

[0175] In yet another variation, a constant negative pressure ismaintained in the area surrounding the distal end of the wave-guide, andcoupling liquid is then supplied to the distal end of the wave-guide. Afluid containment structure is then placed over the waive-guide so thatthe coupling liquid comes into contact with a bottom surface of thefluid containment structure. The fluid containment structure may havemultiple wells and may contain source fluids in one or more of thewells. An acoustic wave is then propagated through the wave-guide, thecoupling liquid, the source fluid containment structure, and into thesource fluid in the well. The acoustic energy then ejects a portion ofthe source fluid from the well. The vertical position of the wave-guidemay be adjusted prior to each fluid ejection. The volume of the couplingliquid above the wave-guide may also be adjusted so that the couplingbetween the fluid containment structure and the wave-guide is notcompromised. After each ejection, the position of the source fluidcontainment structure and/or the target may be adjusted by sliding ormoving them laterally in the X/Y plane. After realignment of a sourcefluid well and a target location with the wave-guide, additionaldroplet, mist, or stream of fluid may be ejected from the source fluidwell on to the target.

[0176] In addition, a procedure for determining the focus as well aspreferred locations for positioning the wave-guide relative to thesurface of the source liquid pool within a source vessel to achieveejection in a controlled and consistent manner will be described below.The wave-guide may be adjusted in a vertical direction to position thefocus of the output acoustic wave on a vertical axis as described above.In one variation, the optimum location to place the focal point may beempirically determined by moving the position of the wave-guidevertically in an incremental displacement relative to the surface of apool of source fluid placed above the wave-guide. This increment, forexample, may be as small as 1 micron or as large as 1 cm. A constantamount of energy is introduced into the wave-guide at each incrementaldisplacement. The condition/size/volume/quality of the dropletmorphology of the ejected liquid, if any, may be recorded by the user ora computer. Through this iterative process, a profile of the amountfluid ejection relative to the position of the wave-guide may beplotted. Such profile may also reveal the actual focus (or focaldistance) of the wave-guide. One would expect the source liquid ejectionat the two extreme ends of the spectrum to be poor, and a region orregions in between to have quality amounts of fluid ejection. Thisregion or regions may then be used to define a preferred range(s) offunctional locations for the wave-guide.

[0177] The user may repeat the above process at the same power inputlevel to acquire more data points for the ejection profile at this powerlevel. Once the user determine the ejection profile at a particularinput power level, the input power may be stepped up or down, and theejection profile at a different level may be determined. During thisejection profile mapping process, the user may supply fluid to thesource fluid pool to keep the source fluid at the same level.Alternatively, the user may prepare multiple source wells, with eachsource well filled to the same level, and after each ejection an unusedwell is positioned above the wave-guide for ejection. In anothervariation, the user may keep the wave-guide in one position and eitherdrain the liquid or add liquid in the source vessel or else raise orlower the source vessel to achieve incremental distances between thewave-guide and the liquid surface. In yet another variation, the systemmay also track the surface level of the source fluid through a fluidlevel detection device, and adjust the wave-guide accordingly in apredefined incremental step relative to the surface of the source fluidto plot the ejection profile.

[0178] Through the ejection profile mapped out in the above iterativeprocess, the user or the computer system, with the assistance ofsoftware, may determine a range or ranges of positions (position of thewave guide relative to the surface of the source fluid) that may be usedfor each fixed amount of energy input.

[0179] The surface level or location of the source liquid may bedetermined through various methods. In one approach, the reflectedacoustic wave after each ejection may be used to calculate the locationof the source liquid surface. A separate acoustic wave may also be sentto provide the “ping” for measuring the location/level of the fluidsurface base on the reflected acoustic wave. Alternatively, if thevolume of the source liquid is known and the dimension of the vessel isalso known, then the location of the source liquid surface may becalculated and tracked during the ejection process. If the size/volumeof the ejected droplet at a particular power level is known, the amountof fluid being removed may be calculated based upon the number ofejections. Displacement of the source fluid surface level may then becalculated based on the amount of fluid that has be removed. A furtherrefinement of the said method may also take into consideration otherfactors that may affect the liquid level contained within the sourcevessel. Examples of such factors include, but are not limited to,evaporation and moisture absorption by the source liquid.

[0180] The control system may tract the source fluid surface level, andadjust the location of the wave-guide when the source fluid surfacelevel is going out of the preferred range defined by the ejectionprofile. Having pre-determined a preferred range for liquid ejection,the system does not have to adjust the position of the wave-guide aslong as the position falls within the preferred range. However, thesystem may also adjust the position of the wave-guide after each andevery ejection.

[b] Droplet Steering Mechanism

[0181] A representative schematic diagram of a droplet steeringmechanism attached to a position adjustment assembly is shown in FIG.13A. As seen, support arm 1304 extends from a platform, which may bemanipulated via, e.g., z-axis adjustment assembly 1306, over a sourceliquid containment structure 1307. A droplet steering mechanism 1305,which operates according to the principles disclosed herein, ispreferably located near the end of support arm 1304 and over theacoustic emitter device 1309. Steering mechanism 1305 is also preferablydisposed beneath or adjacent to a target device 1308. As appliedthroughout, any number of structures may be movable along their x-, y-,or z-axis relative to one another, e.g., droplet steering mechanism 5,liquid containment structure 1307, target device 1308, acoustic emitterdevice 1309, may all be separately movable relative to one another oronly certain structures may be movable depending upon the desiredapplication. A detailed description of a droplet steering mechanism 1305is disclosed in U.S. patent application Ser. No. 10/282,790 entitled“Apparatus and Method For Droplet Steering” filed Oct. 28, 2002, whichis incorporated herein by reference in its entirety.

[0182]FIG. 13B shows a representative schematic of throated structure1310 which illustrates, in part, the general operation of the dropletsteering mechanism. Generally, throated structure 1310 may comprise anozzle 1312 which defines throat 1314. Nozzle 1312 is preferably aconverging nozzle, as described in greater detail below, having an inletor entrance port 1316 and a preferably smaller outlet or exit port 1318.A vectored or directed gas stream, as shown by flow lines 1320, may bedirected into inlet 1316 to be drawn through the structure 1310. Asnozzle 1312 converges in diameter closer to outlet 1318, gas stream 1320may increase in velocity and as stream 1320 approaches outlet 1318, itis preferably drawn away from the centerline 1317 of nozzle 1312 throughdeviated air flow channel 1322. Gas stream 1320 may be drawn away fromthroat 1314 at a right angle from the centerline 1317 of nozzle 1312 orat an acute angle, as currently shown. Gas stream 1320 may then continueto be drawn away from throat 1314 through outlet 1324 either for ventingor recycling through inlet 1316 again. Gas stream 1320 may comprise anynumber of gases which are preferably inert, e.g., air, nitrogen, etc.,or a mixture thereof. However, a reactive micro-droplet mist stream witha combined gas mixture containing micro-droplets may also be used as gasstream 1320. These micro-droplets in the mist stream are preferablyabout 100 times smaller than ejected droplet 1326 and may have specificproperties that cause specified reactions to ejected droplet 1326.

[0183] As droplet 1326 is ejected from the surface of the liquid, itwill have a first trajectory or path 1328. If the trajectory angle ofdroplet 1326 relative to a centerline 1317 of nozzle 1312 is relativelysmall, i.e., less than a few degrees off normal, droplet 1326 may passthrough outlet 1318 and on towards target 1308 with some degree ofaccuracy. If the trajectory angle of droplet 1326 is relatively large,i.e., up to about ±22.5°, droplet 1326 may be considered as being offtarget. However, with gas stream 1320 flowing through structure 1310, adroplet 1326 may be ejected from a well located below structure 1310. Asdroplet 1326 enters inlet 1316 off target and as it advances further upinto structure 1310, droplet 1326 is introduced to the high velocity gasstream 1320 at the perimeter of the interior walls of nozzle 1312, asseen at the point of capture 1330. Gas stream 1320 accordingly steers orredirects the momentum of droplet 1326 such that it obtains a second orcorrected trajectory 1332 which is closer to about 0° off-axis. The gasstream 1320 at deviated channel 1322 is drawn away from the centerline1317 of nozzle 1312 and although droplet 1326 may be subjected to thedeviated vector of gas flow 1320, droplet 1326 has mass and velocityproperties that constrain its ability to turn at right or acute angleswhile traveling at some velocity, thus droplet 1326 is allowed to emergecleanly from outlet 1318 with high positional accuracy. Throatedstructure 1310 may correct for droplet 1326 angles of up to about±22.5°, but more accurate trajectory or correction results may beobtained when droplet 1326 angles are between about 0°-15° off-axis forthe given velocity, droplet size, and mass present in the currentsystem. For example, a given droplet 1326 of water having a velocity ofabout 1-10 m/s, a diameter of about 10-300 microns with a volume ofabout 0.5-14,000 picoliters, and a mass of about 500 picograms(500×10-12 grams) to 14 micrograms (14×10-6 grams) may have itstrajectory correctable within the angles of ±22.5°, but the angles ofcorrection are subject to variations depending upon the mass andvelocity properties of the droplet 1326.

[0184] The use of such a system is not limited by the type of dropletejection operation. For instance, droplets may be ejected with theacoustic emitter device 1309 in either pulsed or continuous motion.Pulsed motion may involve having a acoustic emitter device 1309 9 moved(relative to the source well plate) in discrete increments from onewell, stopped long enough to emit acoustic energy into an individualwell, and then moved again to another well to repeat the process(alternatively, the source well plate may move on top of a fixedacoustic emitter device). On the other hand, continuous motion generallyinvolves moving acoustic emitter device 1309, and/or the well plate, ina constant motion while simultaneously emitting acoutic energy whenpositioned over a desired well to eject droplets. The droplet steeringmechanism is not limited by the type of droplet ejection process but maybe utilized in either, or any other type, of ejection process.

[0185] An example of droplet steering mechanism 1370 is shown in use inFIG. 13C. Main body 1340 is preferably located above the source liquidwell plate 1372 which may contain a number of wells 1374 each having apool of source liquid 1376, which may or may not be the same liquidcontained in each well 1374. Target device 1378 preferably comprises amedium which is perpendicular to a longitudinal axis defined by thethroated structure. Target device 1378 may comprise any medium, e.g., aglass slide, upon which droplets of liquid are desirably disposed and ispreferably disposed above main body 1340, specifically above outlet1318, for receiving the droplets ejected from source liquid 76.

[0186] Target device 1378 may comprise of a well plate as shown in FIG.13C. Target well plate 1358 may be configured to have any number ofindividual target wells 59 for receiving droplets from different sourceliquid 1376 below. Moreover, target wells 1359 may be formed intovarious size wells which can correspond in size and relative spacingbetween wells 1359 to wells 1374 within the source well plate 1372, orthey may alternatively be formed smaller or larger in size and relativespacing between wells 1359 depending upon the desired results.

[0187] In operation, droplet 1326 is ejected from source liquid 1376 byvarious methods, such as acoustic energy. Once ejected, droplet 1326enters main body 1340 through inlet 1316 along a first trajectory orpath 1328. The flow of gas, as shown by flow lines 1320, may be seen inthis variation entering main body 1340 also through inlet 1316, althoughthe gas may enter through separate gas inlets defined near the proximalend of nozzle 1312 in other variations. As the gas is directed throughmain body 1340, as shown by flow lines 1320, it may inundate droplet1326 and transfer momentum to droplet 1326 to alter its flight path to asecond or corrected trajectory 1332 such that droplet 1326 passesthrough outlet 1318 with the desired trajectory towards target 1378.Meanwhile, the gas is preferably diverted away from the centerline 1317of the throat near outlet 1318 along air flow channel 1322, throughrouting outlet 1348, and out through gas outlet 1350. If droplet 1326enters main body 1340 with a desirable first trajectory 1328, i.e., atrajectory traveling close to or coincident with the centerline 1317 ofthe throated structure, droplet 1326 may experience little influencefrom flow lines 1320 and accordingly little correction or steering, ifany, may be imparted to droplet 1326. The gas may be pushed throughmechanism 1370 through positive pressure via a pump (pump is not shown)that is connected to the main body 1340 or preferably the gas may bedrawn through the system through negative pressure via a vacuum pump(vacuum pump is not shown) connected to the main body 1340 through gasoutlet 1350.

[0188] During the droplet 1326 ejection process, if source liquids 1376in wells 1374 are subjected to continuous or continual exposure toacoustic energy, the source liquids 1376 may be inadvertently heated asa result. Heating of the liquids 1376 may be an undesirable consequencesince liquid properties may be altered. Therefore, the liquids 1376 maybe maintained in each well 1374 at a constant predetermined temperatureby controlling the overall temperature of source well plate 1372. Thismay be accomplished through various methods such as maintainingconductive thermal contact between a heat sink (not shown) and sourcewell plate 1372. Alternatively or additionally, the coupling medium 1311may be maintained at a constant temperature through various heating andcooling methods, e.g., compressors, Peltier junctions, etc. Maintainingcoupling medium 1311 may help keep the contacting source well plate 1372at a constant temperature through conductive thermal contact between thetwo. Moreover, to maintain constant temperatures (or to altertemperatures) the steering gas, as shown by flow lines 1320, may beheated or cooled appropriately by the use of, e.g., heat exchangers.Droplets 1326 which are ejected from source liquids 1376 may thus beheated or cooled by the steering gas as droplet 1326 traverses throughnozzle 1312. Another alternative may include having target device 1378or target well plate 1358 heated or cooled appropriately. For example,as seen in FIG. 13D, a heating or cooling unit 1379, e.g., a Peltierjunction device which may be powered by a separate or common powersupply 1377, may be in thermal contact with target device 1378 toprovide the temperature control. Any one of these methods may be usedindependently or in combination with one another, depending upon thedesired results.

[0189] For instance, examples of some of the possible combinations whichmay be utilized using any of the devices and methods as discussed abovemay include the following. One variation may include maintaining oraltering the temperature of soruce well plate 1372 while alsomaintaining or altering one of the temperatures of coupling medium 1311,the steering gas, or target device 1378. Alternatively, coupling medium1311 may have its temperature maintained or altered in addition tomaintaining or altering one of the temperatures of the steering gas ortarget device 1378. Furthermore, the steering gas may have itstemperature maintained or altered in addition to maintaining or alteringthe temperature of target device 1378. Alternatively, each of thetemperatures of source liquid well plate 1372, coupling medium 1311, thesteering gas, and target device 1378 may each be maintained or alteredin combination with one another. These examples are merely illustrativeof the possible combinations and are not intended to be limiting.

[0190] The main body 1340 may be further mounted or attached to aplatform which is translatable in a plane independently from source wellplate 1372 for use as a fine adjustment mechanism as droplets 1326 areejected from the various source liquid 1376 in each of the differentwells 1374. The translation preferably occurs in the plane which isparallel to the plane of source well plate 1372, as shown by thedirection of arrows 1352 which denote the direction of possiblemovement. Although arrows 1352 denote possible translation to the leftand right of FIG. 13C, movement may also be possible into and out of thefigure. The degree of translation may be limited to a range of at least±2 mm from a predetermined fixed neutral reference point initiallydefined by the system. Main body 1340 may also be rotatable, as shown byarrows 1354, about a point centrally defined within main body 1340 suchthat inlet 1316 is angularly disposed relative to the plane defined bysource well plate 1372.

[0191] In operation, source well plate 1372 may be translated using,e.g., conventional linear motors and positioning systems, to selectivelyposition individual wells 1374 beneath main body 1340 and inlet 1316. Assource well plate 1372 is translated from well to well, time is requirednot only for the translation to occur, but time is also required for thesource well plate 1372 to settle into position so that well 1374 isaligned properly beneath inlet 1316. To reduce the translation andsettling time, main body 1340 may also be independently translated suchthat as source well plate 1372 settles into position, main body 1340tracks the position of a well 1374 and aligns itself accordingly. Mainbody 1340 may be aligned by use of a tracking system such as an opticalsystem, e.g., video camera 1356, which may be mounted in relation tomain body 1340 and individual wells 1374. Video camera 1356 may beelectrically connected to a computer (not shown) which may control themovement of the platform holding main body 1340 or main body 1340 itselfto follow the movement of source well plate 1372 as it settles intoposition. Aside from the translation, main body 1340 may also rotateindependently during the settling time of source well plate 1372 toangle inlet 1316 such that it faces the preselected well 1374 at anoptimal position. The fine adjustment processes, i.e., translationeither alone or with the rotation of main body 1340, may aid in reducingthe time for ejecting droplets from multiple wells and may also aid inimproving accuracy of droplets deposited onto target device 1378.

[0192] To further facilitate the droplet trajectory correction, anothervariation of droplet steering mechanism 1380 is shown in FIG. 13D, whichshows the main body 1340 and target device of FIG. 13C with anadditional electrically chargeable member 1382. Electrically chargeablemember 1382 may comprise any electrically chargeable material, such asmetal, and is preferably formed in an elongate shape, e.g., such as apin. Member 1382 is preferably electrically connected to voltagegenerator 1386 which may charge member 1382 to a range of about500-40,000 volts but is preferably charged to about 7500 volts. Inoperation, as member 1382 is electrically charged, the distal tip 1384becomes positively charged. As droplet 1388 travels up to target device1378, it becomes subjected to a high voltage static field and becomespolarized, as shown by the positive (+) and negative (−) charge ondroplet 1388. The charge on distal tip 1384 and on droplet 1388 producesa dipole moment which acts to further influence the trajectory ofdroplet 1388 to travel towards the position of tip 1384. Thus,positioning of distal tip 1384 at a desired location above target 1378allows for even more accuracy in depositing droplet 1388 in the desiredposition on target 1378 to within 10-50 μm. Droplet 1388 behaves as adipole moving through an electric field in relation to distal tip 84which preferably acts as a point charge.

[c] X/Y Linear Stage Assemblies

[0193] Various actuator and displacement device that can providetwo-dimensional motions, which are well known to one skilled in the art,may be implemented here to provide movement to the handling device. Inone variation, a X/Y linear stage along with its corresponding handlingdevice is adapted for transporting well plates in and out of the processarea above the acoustic emitter device and also to and from the wellplate storage queue for load/unload. The X/Y linear stage may alsoprovide sufficient freedom of movement within an X/Y plane so that eachwell on the well plate may be aligned with the acoustic emitter device.

[0194] One variation of an X/Y linear stage is described in detailbelow. The X/Y linear stage, as shown in FIG. 14, may be designed with alow profile and small footprint and could move a well plate in the X andY direction with high running accuracy, high speed, and highacceleration. The X/Y linear stage may comprise two signal-axis linearstages assembled so that their line of action is at 90 degree to oneanother. Each single-axis stage is comprised of a base plate, a linearrail/carriage system, a moving coil/fix magnet linear motor, and limitand position sensors. A load arm is provide on one of the linear stageto which an holding device may be attached.

[0195] In this variation, the X-axis motion is provide by the line ofaction of the larger linear stage serving as the base of the linearstage assembly. The larger linear stage has a dual rail system 1402 withfour linear bearings. The dual rail and four linear bearings may providestability to the load arm 1404when the load are is moved in the Xdirection. The Y-axis motion is provided by the line of action of thesmaller single-axis stage attached to the larger linear stage 1408. Thesmaller linear stage has a one-rail 1410 system with two linearbearings. Aluminum may be used to fabricate some of the parts tominimize the weight of the system. The load arm 1404 may be fabricatedfrom an aluminum thin wall rectangular tube.

[0196] In one particular variation, the X/Y linear stage has a maximumspeed of 5 m/sec, acceleration of 2.5 g, stroke in the X direction of340 mm, stroke in the Y direction of 100 mm, load on the Y directionlinear motor is 3 kg, and load on the X direction linear motor is 10 kg.The X/Y linear stage has a base plate where the X-direction linear motorand X-direction rails are mounted. Two rails for the X-direction aremounted on a precision base block. Four linear bearings (two on eachrail) are running over the two rails. These bearings are connected toeach other and to the X-direction linear motor 1412 to make up theX-direction carriage. The X-direction carriage also works as the basefor the Y-direction rail and linear motor. Two linear bearings arerunning over the Y-direction rail. These bearings are connected to eachother and to the Y-direction linear motor to make up the Y-directioncarriage. The handling device arm is mounted to the y-directioncarriage.

[0197] Each carriage assembly (X and Y) may have limit sensors 1422 andhard stops 1424 on both ends to limit the stroke, an encoder 1426 todetermine position of the carriage at any moment of the movement, and ahome mark 1428 to establish a repeatable zero point (or referenceposition) when the machine is started up and during the process whenneeded.

[0198] There may be two cable tracks 1430 on the X/Y stage to providesafe cable routing. All cables and air tubes from handling device may berouted through handling device arm then joined with cables from theY-direction linear motor and encoder and going through the top cabletrack. When they exit it they may join with cables from the Y-directionlimit sensor, X-direction encoder and X-direction linear motor and enterthe bottom cable track.

[d] Handling Device—Attached to the X/Y Stage Assembly

[0199] Various clamps, compression device, or non-compression holders orcarriers may be implemented on the X-Y linear stage assembly forretrieving well plates from their storage queues. One variation of ahandling device, a gripping assembly, is described in detail bellow.

[0200] The gripper assembly along with the X/Y linear stage performs thefunctions of retrieving/replacing well plates from/to the elevators(storage queues). The gripper assembly 1512, as shown in FIG. 15A, holdsthe well plate 1514 in a secure, predictable, and repeatable mannerduring transport of the well plate into and out of the central processarea of the liquid transfer apparatus. FIG. 15B shows the gripperassembly 1502 without the well plate. In one variation, the liquidtransfer apparatus has two grippers, a source gripper and a targetgripper. The two gripper mechanisms may have similar design such thatthe two mechanisms comprise of approximately 80% common components. Inone variation, the two gripper mechanisms may be identical. In anothervariation the target gripper is mounted inverted in liquid transferapparatus in relation to the source gripper.

[0201] The gripper surfaces that come in close proximity to or contactwith the well plate may have a slim vertical profile allowing them tofit into the elevator, between closely spaced shelves 1542, which holdthe well plates, as seen in FIG. 15F. FIG. 15G illustrates a gripper1512 interacting with an elevator and locking on to a well plate on oneof the shelves 1542 to retrieve the well plate.

[0202] Furthermore, in one particular design, the gripper 1512 in theopen condition (well plate ungripped or released) clears all elevatorcomponents 1544 and well plates, as shown in FIG. 15H, allowing theelevator to move vertically without withdrawing the gripper out fromwithin the elevator area. This design feature may speeds up the time todrop off one plate and then pick up another. The elevator does not haveto wait for the gripper/stage to move and clear the area before it canmove to another location on the elevator.

[0203] In another variation, the gripper grips a well plate with twolinear moving axes 1501, an X-axis (transverse motion when viewed fromthe front of liquid transfer apparatus) and a Y-axis (longitudinalmotion when viewed from the front of the liquid transfer apparatus).Each axis may be guided by linear bearings and driven by pneumaticcylinders with a spring return, as seen in FIG. 15C. The X-axis maypress the well plate against a single fixed pin 1504, while the Y axismay press the well plate against two fixed pins 1502. These three fixedpoints (forming a wedge) may define the well plate position on ahorizontal plane. By always biasing the plate against these stationaryfeatures, the “fixed points” being anchored on the gripper body,excellent position repeatability may be achieved within the gripperhold, each time the same well plate is garbed and secured in the gripperassembly. This design feature may also provide consistency in theposition the gripper grabs different well plates having the samedimensional specification. For example, each well plate may be grabbedin the same way, in approximately the same location.

[0204] In one variation, the gripper's two axes are driven open bypneumatic air cylinder and closed by compression spring 1505. Thisconfiguration may provide fail-safe operation wherein a well plateremains securely gripped in the event of a system failure, power outageor loss of pneumatic pressure. Each pneumatic cylinder may have twoposition sensors attached: one sense fully open condition, the otherfully closed position. The position in which a well plate is properlygripped is between open and closed and there for doesn't trigger eithersensor. FIG. 15D shows the pneumatic air cylinder being activated torelease a well plate.

[0205] The gripper assembly may also include a set of three fine-threadscrew 1506 assemblies providing leveling and positioning functions forthe gripper as an assembly. Mounted between the gripper body and themounting interface, the tree assemblies can be adjusted uniformly ordifferentially. Uniform adjustment moves the X-Y plane of the gripperassembly up and down in the Z direction with respect to the liquidtransferring apparatus. Differential adjustment tilts the X-Y plane ofthe gripper with respect to the X-Y plane of the liquid transferapparatus. The mounting interface 1508 of the gripper may utilizeprecision locating pins to allow for simple yet precise removal andreplacement of the gripper from the X/Y linear stage assembly.

[0206] Furthermore, three horizontal surfaces 1506, one on the moving Yarm and two at the Y fixed pins 1564, may define the horizontal planeX/Y for the well plate to be secured in the gripper. The horizontalsurfaces may have lead-in ramps 1562, which allow a well plate to bepicked up even if the well plate is poorly aligned with the gripperassembly.

[0207] In one variation, the three horizontal surfaces defining the X/Yplane for the well plate are located on three Y-axis fingers. Each ofthe three Y fingers have a flat surface, paralleled to the X/Y plane, onwhich a griped well plate rests, defining the Z position of the wellplate. Since two of the surfaces, located on two fixed fingers 1502, arestationary, and the third moving surface, located on one moving finger1503, is guided by precision linear bearing, the positionalrepeatability may be very good. The fixed and moving well plate contactfeatures, or fingers, on each gripper assembly, may including rampfeatures 1562, as seen in FIG. 15E. The ramp 1562 or angled lead-insurface to guide the well plate as it is being gripped. With long X andY strokes and generous finger lead-in surface, the gripper can grasp awell plate that is poorly aligned (e.g., tilted from the X-Y plane ofthe gripper) relative to the gripper. The three Y-axis finger sets maybe removable and replaceable. This may allow the gripper to be adaptedto various well pates and microtiter plates that are commonly used inthe industry by simply replacing the figure set with an appropriatematching finger set.

[e] Storage Queues

[0208] In one variation the storage queues comprise of elevators locatedwithin the liquid transfer apparatus for holding the well plates.Computer and/or feedback control mechanisms maybe connected to theelevator's actuator or displacement mechanisms for queuing of wellplates in an automated process system. Barcode scanner may be integratedwithin the elevator such that the bar code on each well plate may bescanned and the system control computer may track the location of eachwell plate within the storage queue. For example, bar code scanner maybe positioned at the level where the gripper assembly retrieves the wellplate. The system may scan the bar code on the well plate to verify thespecific well plate being retrieved each time. The elevator may movevertically and transport specific well plate in the storage queue to agripper presentation position for access by the gripper assembly. Whenthe well plates within the elevator queue are not in use, the elevatormay be lowered into a storage and/or climate cavity within the liquidtransfer system. In one variation, there are two elevators, one forsource well plates (left position from the front of the liquid transferapparatus) and one for target well plates (right position from front ofthe liquid transfer apparatus). The two elevators may be constructed ofthe same mechanisms.

[0209] The elevator may comprise of a vertically mounted, linear motionassembly, a well plate back plane 1622 with individual shelves 1624 forwell plates, and a sliding seal assembly 1626, as shown in FIG. 16. Theback plane is the plate at the back of the storage queue where each ofthe individual shelves 1624 mounts. The linear motion assembly maycomprise of two linear beating units, a ball-screw drive, and aservomotor 1632 with an integral brake that provides load holding whenthe elevator is not in motion. In one variation, the well plate backplane 1622 may have as few as one shelf for a single well plate, or upto twelve shelves for twelve well plates. With an extended linear systemand backplane, additional well plate capacity may be implemented in theelevator assembly, as one skilled in the art would appreciate. Differentshelves may be interchanged on the elevator backplanes to storedifferent varieties of well plates. A sliding seal 1626 assembly may beprovide to maintain separation between the climate controlled area 1642of the system where well plates reside, and the non-climate controlledarea 1644 where the servomotors 1632, linear systems, and relatedcomponents reside.

[0210] In one design variation, the elevator storage queue is normallypositioned down in the lower storage area 1646 below the processing deck9. The storage queue may be moved up so that each well plate within thestorage queue may be scanned when it passes a barcode reader, which maybe positioned just beneath the processing deck. Alternatively, thebarcode scanner may be positioned above the processing deck. The storagequeue may also move up above the processing deck to present a well plateto the gripper for entry into the process area. Barcode scanning mayalso take place while the storage queue is being raised for presentationof well pates for processing.

[0211] The elevators may also be completely raised above the processingdeck to present all the shelves in the elevator for manual (operator)insertion, removal and/or replacement of well plates. In anothervariation, modularized rack may be provided such that a complete set ofwell plates (e.g., set of 8 or 12 well plates) may be inserted orremoved from the elevator queue. In yet another variation, the elevatormay receive one or more modularized queues or racks. For example, eachelevator may be designed for receiving one 12-plate rack, or two 6-plateracks, or three 4-plate racks. In another design variation, access tothe storage chamber below the processing deck is provided, such thatoperator may replace the well plates while the elevator queue is sittingin the storage chamber below the processing deck.

[f] Image Detection System

[0212] The image detection system may be used as an alignment device toprecisely align the source and/or target well plates to the verticalaxis of the acoustic emitter device. The image detection system may alsobe implemented for tracking the liquid ejection process and/or providepost ejection liquid transfer verification. Furthermore, the imagedetection system may also be used for monitoring and or measuringreactions within the wells by detecting and/or recording signal due tochemical reactions, fluorescent markers, or other reactions which emitslight or changes transmission or absorption of lights in substanceswithin the well. Other light sources may also be adapted within thesystem to enhance the capability of the image detection system. Forexample, IR beam may be position below the well plate, which is alignedwith the imaging system, for measurement of IR abortion of materialswithin the wells. In another variation, UV light source (e.g., a xenonlamp) may be positioned above the well plate that is aligned with theimaging system, for exciting fluorescent markers. Other light sourceand/or corresponding chemical markers well known to one skilled in theart may also be adapted for used in the present invention.

[0213] In one variation, the image detection assembly is comprised of adigital camera 1702 mounted on the end of an optical tube 1704; as seenin FIG. 17A. A lens assembly 1706 may be mounted on the opposite end ofthe optical tube 1704. The entire tube assembly may be mounted on alinear slide carriage 1708 with two clamps. The linear slide may bedriven with a servomotor 1710 in the z-axis (in the vertical direction),so that the camera 1702 is able to focus on objects that are sitting ondifferent levels/planes. A linear slide may be mounted on a block 1712that has alignment features used to align the camera with thetransporter. The lens assembly may have an LED light source 1714 inorder to illuminate the object being viewed. Other light source (e.g., ahalogen light bulb) may also be used to provide illumination. In onevariation, an IR LED light source may be used to illuminate the objectbeing viewed. Appropriate filters may be implemented to filterextraneous light, and thus, provide good contrast ratio in the imagecaptured by the image detector. For example, IR light may be implementedto illuminate the fiducial marks on the source and target well plates.Corresponding high-pass and/or low-pass optical filter may beimplemented to improve the signal-to-noise ratio for the illuminatedfiducials. The filters may improve the contras ratio between thefiducial mark(s) and its surrounding area on the well plate. Otherfilters, both optical and digital, that are well known to one skilled inthe art may also be implemented to enhance the edge detection capabilityof the image detection system.

[0214] Alternatively, a UV light source may be used to provide photoexcitation. In one variation the fiducial marks are coated with UVexcitable materials. In another variation the chemical in the sourceliquids are tagged with UV excitable chemical markers. Light splittingdevice (e.g., a light-splitting prism) may also be implemented to directilluminating light source down the camera's focus path. A lightsplitting device may also be implemented to diver part of the lightgoing toward the camera to a separate light/image detection/recordingdevice. The camera axis of the image detection assembly may be mountedin such a way that it remains fixed to the center axis of thetransporter assembly (wave-guide/fluid basin unit).

[0215] In one variation, the image detection assembly attached to aprecision angle alignment mount that sits on a X/Y alignment mount 1722.The X/Y alignment mount may provide a rough alignment in the X and Ydirection, and precision angle alignment mount 1724 provides rotationalfreedom in the X/Z plane, so that operator may manually adjust theposition of the image detection system to align it with the acousticemitter device. Actuators may also be adapted to the adjustable mount sothat the alignment of the image detection system may be corrected by acomputer.

[0216] In another variation, the source or target well plate is movedunder the camera to four taught (or predefined in the control system)positions, one at a time, so that fiducial at each of those fourpositions is in the camera's field of view. The vision system capturesan image of each fiducial. Then the software calculates the fiducial'spixel location in the image, in pixel coordinates (or the systemsreference coordinates). By using the camera calibration factor thesepixel locations may be converted into X-Y coordinates (world coordinatesystems). Software may then use these four fiducial locations todetermine the orientation of the source and target. These source andtarget orientation data may then be implemented to calculatedorientation angle to move to specified source and target locations, sothat source and target locations are in line with the acoustic emitterdevice and the camera center.

[0217] In another variation, the fiducial marks are configured ofmaterials with suitable contrast differential compared to thesurrounding area (or background) of the fiducial marks. For example,white fiducial marks may be implemented on a black well plate.Alternatively, the marks may be black while the well plate is white. Itis preferable that there is a high contras ration between the fiducialmark and its immediately surrounding area.

[0218] In another variation, two-dimensional circular dots and/orthree-dimensional spherical features 1732 may be placed at the cornersof each well plate 1734 to serve as fiducial markers. Spherical featuresare particularly useful since only reflected light on the optical axis1736 of the image system will be detected by the detector 1738. Thecenter of the sphere provide good reflection while the peripheral areatend to reflect light at an angle from the image detector's axis 1736and away from the image detector, as illustrated in FIG. 17B. Thisresult in a sharp image of a fiducial mark created by the sphere whichmay be easily capture and processed by the image detection system.Comparing the spherical feature to a flat circular feature, a flatsurface surrounding the circular feature tend reflect more light and maycause an edge-effect where the circular feature comes into contact withits surrounding area, and thus, causes a loss of resolution.

[0219] In one variation, the spherical features 1732 are reflectivespheres (e.g. metallic spheres) position on or within a well plate. Itmay be beneficial to place the spherical features within the well platessince the reflective surface of the sphere will be protects fromabrasion or other damages when well plates are handled or stacked forstorage or transport.

[0220] In one example, holes are drilled in the four corners of a wellplate 1734 and then stainless steel ball bearings 1740 are pressed intoeach of the four holes, as illustrated in FIG. 17C. When viewed by theimage system, excellent contrast may be achieved between the well plateand the ball bearing. In addition, since the ball bearing is spherical,pin-point reflection of light is captured by the image detector, sincethe center region 1742 of the sphere produce good light reflection onthe Y-axis and the peripheral region 1744 of the sphere reflects lightway from the Y-axis, as seen in FIG. 17D. Thus, the image captured bythe image detector may be smaller than the diameter of the ball itself.It is preferable that the fiducial is a highly reflective surface with asmall area reflecting light back to the image detector to create a sharpimage with high contras ration with the background.

[0221] As an alternative to fiducial marks, existing features on thewell plate may be used as fiducial or registration marks. For instance,the image detection system may detect the edges of a selected well(e.g., the well in the first row and first column) and the softwarecould calculate a point representing the center of the well. A secondwell (e.g., the well in the first row and in the last column) may alsobe detected and its center calculated. Base on the position of thecenter of the two wells the system may then map out the position of thewell plate on the X-Y plane.

[0222] Although an image detection system is implemented in the abovevariations for detection of source and/or target plates' location, oneskilled in the art would appreciate that other object detectionapproaches may also be implemented along with the image detection systemor in place of the image detection system. For example, acousticdetection, optical/laser detection, capacitive, inductive or pressuresensing approaches that are well known to one skilled in the art mayalso be implemented independently or in combination to facilitate thealignment of source/target plates. Efficient and effective detection ofsource and target plates allows alignment of selected source well andselected target well with the acoustic emitter.

[0223] In one variation, arrays of laser sources and arrays ofcorresponding sensors are configured above the acoustic emitter fordetection of source and target plate positions. The laser/sensor arraysmay form a three dimensional matrix and capable of determining thespecific locations within this matrix that are occupied by an object.The position and/or orientation information of the plates is collectedby a computer for calculating the amount of misalignment. Base on theposition information from the detectors, the computer may generate acoordinate system representing the source or target plate, and then,through comparison with a standard coordinate defined by the system beable to precisely position the plate within the standard coordinate.Thus, base on the coordinate information the computer will be able tocontrol the X/Y linear stages and their corresponding handling devicesto align a specific well on the well plate with the acoustic emitter.

[0224] In another variation, actuators are placed around an area abovethe acoustic emitter. When a plate is moved into the ejection area abovethe acoustic emitter, the edges of the plate will apply pressure to theactuators, thus allowing the computer connected to the actuators todetect the position of the plate. For example, the actuator may be placein a “L” shape configuration, and the source or target plate is placewithin this L shape boundary when the plate is slide into itspre-assigned position above the acoustic emitter. The pressure ordisplacement exerted on the actuators along the “L” shape boundaryallows the computer to calculate the amount of misalignment on the X/Yplane and make necessary adjustments to ensure proper alignment betweenthe source plate, the target plate and the acoustic emitter. As oneskilled in the art would appreciate, the actuator and/or other sensorsmay be placed in various other configurations for detection of thesource and target plates' position.

[0225] In yet another variation, electromagnetic waves, sound waves orlight waves are propagated toward a source or target plate place abovethe acoustic emitter. The reflected sound or light wave is capture bysensors and used to calculate the position of the plate.

[0226] In one variation, the acoustic wave emitter for liquid ejected isalso used for the detection of the source fluid containment structure'sposition. Acoustic waves are propagated from the acoustic wave emitterthrough the coupling medium toward the fluid containment structure. Thereflected acoustic wave is captured by a sensor and processed by acomputer to determine the position of the source fluid containmentstructure.

[0227] Makers, fiduciary markers, other energy reflective/absorptivetargets, and/or other two or three-dimensional features may be place onor within the source and target plates to assist the correspondingsensors to detect the source and target plates during the alignmentprocesses. For example, a prism or other refractive materials may beplace on the corners of each well plate. When the well plate is positionabove the acoustic emitter, a laser beam is directed into one side ofthe refractive material and exits the other side. A sensor is positionto detect the angle of the exiting laser, and base on this informationthe amount of misalignment may be calculated. The position of the wellplate may then be adjusted so that proper alignment may be achieved.

[g] Machine Controls, Electronics and Software

[0228] A control system may be provided to provide overall control ofvarious components and device in the liquid transfer apparatus. In onevariation, the control system comprises a single board computer mountedon a computer rack mount chassis with a passive back plane. The computerboard may have PCI and ISA bus where additional controller may beconnected to the main control system. FIG. 18A illustrates one variationof a control system layout with centralized control for all the controlcomponents. A motion controller may be implemented to control the 8 axesof motion in the X/Y linear stages, storage queue elevators, camerafocus, and acoustic emitter focus. All of the axes may have an encoderto provide precise location feedback, and home and over-travel sensorsfor setting a reference location and prevent over extension of themechanisms, respectively. An RS 232 controller may be implemented tocommunicate with the barcode scanners, which scan barcodes on the targetdevices and the source vessels. A RS 485 controller may be implementedto send commands to controllers for controlling relative humidity,temperature and/or inner gas pressure in the process area. A signalsynthesizer may be used to generate an electric signal, which isamplified by an amplifier to drive the acoustic emitter device. Thesignal synthesizer may be any signal generator, well known to oneskilled in that are, that is able to generate a signal of desiredfrequency and amplitude. An amplifier may be provided to amplify thesignal to appropriate amplitude to drive the acoustic emitter device ifthe signal coming out of the signal generator does not have enoughstrength. A high-speed analog to digital controller is used for readingsignal back from the acoustic emitter device. Software may beimplemented to process the feedback signal in order to determine theoutput signal for the signal synthesizer. There may be one highbandwidth analog-to-digital controller. There may be a digital I/Ocontroller for monitoring and controlling all the digital I/O signals onthe machine. There may also be an analog 1,0 controller for monitoringand controlling all the analog I/O signals on the machine. The analogI/O controller may be used for controlling devices that are controlledby analog voltage, and also used for reading low bandwidth analogsignals. A vision controller may be implemented for garbing images fromthe camera system and feeding the digitized image to an image processingsoftware for processing (e.g., feature extraction, image measurements,pattern recognition).

[0229] Various software may be implement in the control system forcontrolling different components, and for processing signals received bythe system. In one variation, a system control program is implemented ona computer within the control system. The software architecture for thisparticular variation of system control program is shown in FIG. 18B.Modular software design is implemented in this system program, whichuses handshakes to communicate among the various modules within thesystem. This flexible architecture allows for relatively easy additionof new modules and relatively easy removal of existing module. Graphicalusers interface, with various menu options, gives the user access tovarious control parameters and allows the user to navigate throughdifferent options easily.

[0230] In this variation, the main interface, which is the highest levelin the menu structure, allows user to login into the software. Once theuser is logged in, user may have various level of access/control of thesystem depending upon the level of access that was prescribed to theparticular user.

[0231] The Operation menu may allow the user to access differentoperations of the machine. For example if user wants to turn thecoupling liquid On/Off or the user wants to change the flow rate of thecoupling liquid, an option may be provide to control such parameters. Inanother variation, the user may be able to prescribe specific locationson the storage queues to retrieve source and target well plates.

[0232] The configuration menu allows the user to configure differentpart so the system. For example, it may allow user to provide sourcevessel and target device configurations. The user may be able to specifylength, width, height, number of row and columns, acoustic parameter formaterial of the source vessel, etc. Software option may allow user toadd, delete, and change user information, including defining user accesslevel. Under machine and process menus, user may configure varioushardware parameters and define variables for the operation process.

[0233] The diagnostic menu allows the user to access digital I/O's,analog I/O's, motion control, and vision system. By selecting thedigital I/O panel, the user may control digital output, and monitordigital inputs. Analog I/O panel allows the user to read analog inputsand send an analog voltage out of an analog output port. The “setting”panel allows the user to specify the volume calibration factor andvolume per drop in picoliter increments for the acoustic ejection of theliquid transfer apparatus. The “motion control” panel allows the user tochange or teach a position specified in the position database. The usermay provide calibration setting or operate the system to teach thesystem location parameters for specific operation to be stored in theposition database. The position database may contain informationdefining a location for fiduciary marker alignment check, a location forretrieving a well plate from a storage queue, and the like.

[0234] User may go to a position where the system had already beentaught by selecting the particular position button. The “modular test”panel provides operation for editing elevator sequence and for testingsystem functionality of the elevator. The “vision system” panel allowsthe user to monitor images being acquired by the vision system in realtime. This panel may also allow user to access camera calibration andimage measurement utilities. In one variation, by using partsmeasurement function, the user may measure a part or object that isplaced on one of the x-y stage under the camera. This may be achieved,for example, by moving the x-y stage precisely so that the centerlocation of the camera focus move from one edge to a second edge of apart or object being track by the image, while simultaneously recordingthe amount of displacement. Alternatively, object measurements may beachieved by pre-calibrating the image system and using image-processingsoftware to calculate the object size base on the image captured by theimage system.

[0235] The help menu provides access to basic help functions that areprogrammed into the system software, and allows user to definedspecialized help functions that may be customized by individual user.The basic help function may additionally have access to on-line help,which may provides user with information on how to run, calibrate andmaintain the machine. It may also provides access to specifications,images, drawings of the different parts of the machine

[0236] The run menu provides different operation modes that may beselected by the user. Submenus are also provided for user to monitorand/or change control parameters for computer controlled operations.

[0237] Software or system program may provide automated and precisioncontrol for the liquid transfer apparatus to achieve high throughputoperation and ensure synchronization between various components withinthe system. Various software architecture and codes well known to oneskilled in the art may be implemented to provide the user interface andsystem controls describe above.

[0238] Software may also be implemented for selecting specific wells onthe source vessel and ejecting the selected source liquid in topredetermined target locations on the target device or target wellplate. User may also program the software with specific ejectionsequence to transfer a series of liquids out of their correspondingwells into a series of receiving target wells.

[0239] In one aspect of the invention, an algorithm implemented in acomputer program may be used to optimize motion profile for the ejectionsequence, so that liquid may be transferred in an efficient manner froma plurality of source well to target wells. For example, the user mayprovide a list of predefined sources and their corresponding targetlocations. The list of source and target locations may be described as amultidimensional array. Each coordinate describes the position of theSource X, Source Y. Target X and Target Y. An additional dimension(e.g., source or target plate ID) may be added if multiple well platesare used for either source or target. A computer program may calculatethe optimal ejection sequence to optimize the performance of the system.In one variation, the computer may calculate the optimal ejectionsequence to minimize the amount of time needed to transfer all theliquids from their sources to their corresponding targets. In anothervariation, the algorithm may sort the list in such a way that the totalmotion required is the shortest total path for the axis that moves thelongest total distant. This may be calculated by adding the distances ofeach move for each axis. For example, assume a coordinate system inwhich the origin of the coordinate system is in the lower left-handcorner of each well plate. Consider four points for simplification:(0,0,0,0), (15,15,0,1), (0,1,0,2), and (15,18,0,3). The total distancemoved for each axis by doing these in the given order is [45, 46, 0, 3].However, by sorting them to the following order: (0,0,0,0), (0,1,0,2),(15,15,0,1), and (15,18,0,3), we have a total distance of [15, 18, 0,5]. Many other sorting techniques, which are well known to one skill inthe art, may also be applied in this system.

[0240] One particular approach, which requires minimal amount ofcomputing time, is described below. Based on the list of source andtarget locations provided by the user, the computer first sorts thesource positions so the ejection sequence moves from left to right andthen right to left on the next row on each well plate; and from the topsource well plate down to the bottom source well plate in thecorresponding sequence in the elevator queue, if the sources reside onmore than one well plate. Once the source sequence is selected, thecorresponding target sequence is determined based on the source targetrelationship defined by the list of source and target locations providedby the user. Since the computer determines the ejection sequence, theuser may provide multiple pairs of source and matching targets in anyorder and let the computer sort out the optimal sequence for processing.

[0241] In another variation, where more than one source liquid is to bedelivered into each target well, and a particular delivery sequence isdesired, the user may prescribe the specific sequence of ejection byentering it into the system directly for processing. Alternatively, moreelaborate sorting/optimizing algorithm may also be implemented todetermine the desired ejection sequence.

[h] Database

[0242] One of the applications of the liquid transfer apparatus is totake liquids contained in one or more source liquid containmentstructures and transfer them to one or more target devices, and beingable to define the precise location to transfer each liquid droplets andat the same time track the liquid transfer process with a database(s).The database(s) allow the user to determine precisely the individualliquid pools that are generated on the target and may also allow theuser to go back and verify the liquid transfer process.

[0243] The source liquid containment structure(s) may have an associateddatabase comprised of a plurality of data inputs, e.g., fluid type,fluid surface tension, fluid viscosity, fluid location (within thecontainment structure), age of fluid (when it was created), where it wascreated, how often it has been used, first time and/or last time used,amount of fluid, etc. The database may allow the user to tie whateverinformation that may be useful to the individual liquid pool on theliquid containment structure. Information regarding each liquidcontainment structure, such as bar code for each structure, may also betied to the other entries in the database.

[0244] A “mapping profile/database” may be provided to instruct theliquid transfer apparatus as to which source liquid it is to transfer towhat target device/target location. The apparatus' internal software maytake this mapping profile and formulate a preferred optimized sequencefor fluid transfer to minimize the time to complete the total number oftransfers.

[0245] In addition, a similar target device or output database may beloaded onto the apparatus. The output database may have similar dataregarding liquids on the target device. In some cases, the outputdatabase might be “empty” because the user is using new/empty targetdevices. In other cases, the user may utilize target devices containingliquid(s), and information regarding each liquid pool and its locationon the target devices may be provided in a database. In cases wherenew/empty targets devices are used, the system may generate a new outputdatabase as needed. Identification or registration information may beprovided to link individual entries in the database to individual targetdevice or a set of target devices.

[0246] After liquids are transferred, both the source and targetdatabases may be updated with new information. In one variation, at theend of the liquid transfer process the liquid transfer apparatusprovides the following information to a database: the source liquidcontainment structures (with less liquid in them), the target deviceswith added liquid, and corresponding database (s) with informationcorresponding to each pool of liquid on the source and target plates.One database may be provided and contain both the source and targetinformation. Alternatively, a source database is provided withinformation regarding all the liquids in all the source plates, and aseparate target database is provided with all the information regardingall the liquids in all the target plates. It is also feasible to provideindividual databases for each source and each target plate.

[0247] In one aspect of the invention, a database is provided to managevarious input and output data. The database may also be used to trackchange in the source liquid library and provide reference informationfor the output target liquid library. The system controller may collectand store data during real-time operation of the machine to trackresource distribution and/or for future analysis.

[0248] In another variation, the database management system comprises amain database and a local database. The main database may contain allthe information that is required by the control system and store thedata collected in real time. As seen in FIG. 19, one variation of adatabase is illustrated. The main database provides various informationto the system controller to support the operation of the system, as seenin “Input to Apparatus” in FIG. 19. In this variation, the main databasereside on a central system, which is separate from the local computerthat controls the liquid transfer apparatus, and provides the liquidtransfer apparatus with source/target well plate information and processrequirements such as a mapping profile. The main database also receivedoutput information from the liquid transfer apparatus, as shown in“Output from Apparatus” in FIG. 19.

[0249] The computer controlling liquid transfer apparatus may maintain alocal database. The local database maintains information that is uniqueto the liquid transfer apparatus, which it supports. The local databasemay include information such as handshake information, which supportscommunication between different mechanisms and devices within the liquidtransfer apparatus, user information, which provides user accessinformation, and position information, which provides operationparameters for the different mechanisms and devices that makes up theliquid transfer apparatus.

[0250] Various information may be provided by the main database tosupport the operation of the liquid transfer apparatus. For example,information regarding the source well plate are provided so the systemmay properly identify specific source wells for liquid ejection.Physical and material characteristics of the plate, dimension of thewell, pitch of the well in X and Y direction (distance between thewells), thickness of the plate at the bottom of each well,characteristic of the source liquid including volume, depth of theliquid and physical and characteristics of the liquid may also beprovided, so that acoustic waves may be appropriately directed toachieve ejection of a portion of the source liquid. Informationregarding the plate(s), the well(s) and the liquid(s) contained withineach well, may allow the control system to calculate the properplacement of the acoustic wave focus and the desirable amount of energyto generate for each ejection. Information regarding the target wellplates may be provided so that the system may properly identify thespecific target location that will receive each ejected droplet ordroplets. Physical and material characteristic of the target well plate,such as material characteristic and dimension and of each well may alsobe provided to assist in the placement and alignment of the target.Information regarding fiducial marks or other feature on thetarget/source plates may also be provided. The fiducial markerinformation may assist the image detection system to locate the marksand facilitate the alignment process. For example, information regardingthe number of fiducial marks on each well plate and the location of eachmark may be provided so that the system may position each mark withinthe focus of the image detector without searching for them.

[0251] In addition, information that is required in the liquid transferprocess may also be extracted from the main database, as shown under“process requirements” in FIG. 19. The user may load a “mappingprofile/database” from the main database in the system, which providesthe system the proper instructions as to which fluid it is to transferto what target device/target location. The system's onboard software mayexecute this profile directly or take this mapping profile and determinea specific sequence to process the liquid transfer based on algorithmsprovided by the user. In one example, the fluid transfer sequence isoptimized to take minimum amounts of time to complete the fluidtransfer. The optimized process sequence may be saved in the databaseand then executed by the system controller.

[0252] In one variation, the mapping profile provided to the liquidtransfer apparatus includes the following information (for each intendedtransfer of liquid between a designated source well to a designatedtarget well): target ID (which identifies a particular target platewhere the target well is located), target row number, target columnnumber (which identifies the location of the target well), source ID(which identifies a particular source plate where the source liquid islocated), source row number, source column number (which identifies thelocation of the corresponding source well where liquid are to betransferred from), volume (the amounts of liquid to be transferred). Forexample, if 100 transfers are called for, the mapping profile may beprovided in a spreadsheet with 100 rows and 7 columns, withcorresponding variable that are listed above in each column.Furthermore, additional columns may be added to provide informationregarding the physical properties of the source liquid in each well.

[0253] In one example, the liquid transfer apparatus processes themapping profile as described below. The apparatus first scans thebarcodes on all the source plates and all the target plates in thestorage queues to determine which well plates are located in the storagequeue and their location in the storage queue. Then the apparatus startsthe liquid transfer process by determining the location of thecorresponding source well for the first target well on the first targetplate in the storage queue by referring to the mapping profile suppliedto the apparatus or the optimized process sequence generated by thecomputer. Once the corresponding source well has been determined, theapparatus retrieves the appropriate source and target well from thestorage queue and effectuate the liquid transfer. The apparatus thengoes to determine the corresponding source well for the second targetwell on the first target plate and then completes the liquid transfer.The apparatus goes on iteratively to process all the target wells on thefirst well plate, then goes on to process the next well plate, until allthe targets has been processed. If a particular target well is to beleft empty the system controller would skip that well and go onto thenext well.

[0254] After each ejection, the system may generate a series of dataentries that may be stored in a database. A collection of these entriesfor all the ejection completed for a given set of source and targetplates may form the basis for an output database. Some of the variablesthat may be recorded includes, time of transfer, which is the time ofvolume transfer for each well; the source and target IDs, which arerecorded to reference/analyze the collected data. If the user selects toperform volume measurements, the volume data will then be recorded. Ifthe protocol includes spot measurement, then the liquid transferapparatus will measure the spot diameter and the location of the liquidthat was transferred onto the target plate, and record the informationin the database for position accuracy and spot size analysis, which maybe performed later.

[0255] In one variation, the following variables are saved in thedatabase after each ejection: Time Stamp—Time at which data is collectedor volume is transferred; Machine Name—Name of the machine, as there canbe multiple machine on the same shop floor; Transporter#—Number of thetransporter used in that machine; Z for LL—Height (or position) of thewave-guide/transporter (acoustic wave ejection unit), at the time ofliquid level measurement; Freq—Spotting frequency; Amp—Spottingamplitude; Return Status—Status return by liquid level function, thattells if the process for finding liquid level was successful; Mode—Thereare different conditions that can be set for finding liquid level, modeis the number that defines those conditions; ErrRecMode—There aremultiple error recovery modes, which can be used depending upon thefeedback from different devices in the liquid transfer apparatus;Result—Actual liquid level measured; Z to Spot—Height of the wave-guide,when spotting took place (calculated); Current Z—Height of thewave-guide, when spotting took place (actual);

[0256] SrcWell-X—Current source location or the column number of thewell; SrcWell-Y—Current source location or the row number of the well;TrgWell-X—Current Target location or the column number of the well;TrgWell-Y—Current Target location or the row number of the well;SrcWPateSNo—Current Source well plate serial number; SrcWplateType—Thisis type of source well plate for which the liquid transfer apparatus isconfigured, which can be 96, 384, 1536, etc.; TrgWPateSno—Current Targetwell plate serial number; TrgWplateType—This is type of Target wellplate for which liquid transfer apparatus is configured, which can be96, 384, 1536, etc.; FluidLevel—Fluid level in the current source well,as entered by the user; Well File—Name of the file that user haveselected to be used for well plate physical characteristics; AutoCorrect—After detecting the liquid level, if liquid transfer apparatusshould auto correct the position of the transporter; User—Name of theuser; CorrRatio—This is the factor which tells the user the confidencelevel of liquid level detection process, higher the number the better itis; Focus—A number that is for the wave-guide and defines its focalpoint in mm; #of burst—The number of spotting bursts used duringspotting process for current transfer of volume; Spot Amp—Measuredvoltage, during spotting process; Spot Delay(us)—This define the usersettable delay, between each spot; Spot Intended—This is defined by theuser for total volume needed to be transferred (# of spots); SpotCounted—Number spots ejected by the HTS-01(actual); Comment—Commentinserted by user to keep track of collected data; Spot IDX—Number ofspots counted by vision system, for each transfer; Src X pos(mm)—ActualPosition of the Source X axis during current transfer; Src Ypos(mm)—Actual Position of the Source Y axis during current transfer;Trg X pos(mm)—Actual Position of the Target X axis during currenttransfer; Trg X pos(mm)—Actual Position of the Target Y axis duringcurrent transfer; Center X(mm)—Center of the resulting target spotdetected by vision system, in world coordinates system (a standardcoordinate defined by the system), in the X direction (mm); CenterY(mm)—Center of the spot detected by vision system, in world coordinatessystem, in the Y direction (mm); Dia(mm)—Diameter of the spot, detectedby the vision system; Special—This field is used for recordingobservation by the vision system. As one skilled in the art wouldappreciate, the user may designate one or more of the variables in theabove list to be recorded by the control system in the liquid transferapparatus. Additional information that the user finds useful may also beassociated with each liquid ejection and recorded in the database alongwith the variables listed above.

[0257] The liquid transfer apparatus may have a local database that isassociated with each liquid transfer apparatus. The local database maycontain information that are unique to the individual apparatus and/orinformation that are useful during the operation of the apparatus. Inone variation shown in FIG. 19, the local database comprises threesub-components: Handshake Database, User Database, and PositionDatabase. The three sub-components provide information that supports theoperation of the apparatus to perform the liquid transfer. The HandshakeDatabase specifies software handshakes between subsystems of the liquidtransfer apparatus. The User Database includes information about username, password and access level to the liquid transfer apparatus'computer controller. The Position Database provides the operationparameters for the various mechanisms in the apparatus.

[0258] For each moving mechanism, such as the X-Y linear stage, the usermay program the system with parameters controlling movement of themechanism. For example, in the program or setup mode, the user may movethe X-Y linear stage to the storage queue access position and allow thecomputer to register that position. The X-Y linear stage may then bemove to the liquid ejection position where the well plate would be abovethe acoustic emitter and the computer system may register the position.The user may also program the system to define the speed andacceleration for the movement of each individual mechanical part foreach movement between a predefined staring position and the predefineddestination position. For example, the X-Y linear stage may beprogrammed to move from the storage queue access position to the liquidejection position at a predefined speed and acceleration. Differentmechanisms (e.g., left elevator, right elevator, source plate X-Y linearstage, target plate X-Y linear stage, vision system, transporter(wave-guide and associated unit)) within the apparatus may have theirown movement parameters defining where and how fast to move each part ofthe device for a particular operation. The position database storesthese functional parameters, which may include position, speed, theirpositive and negative directional limits, and acceleration information,for all the mechanisms and their associated functional operation. When aparticular mechanism is to be moved to a predefined location (e.g. aposition that was taught to the system), the stored functionalparameters are retrieved from the database and executed by the system.

[0259] The position database may be programmed with a default set ofparameters. The user may then reprogram and/or teach the system withrefined position information to improve the operation of the system. Theprogram may have predefined upper and/or lower programming limitationthat prevents the user from operating the system beyond its mechanicallimitations. The local database may also record performance or equipmentoperation information so that system performance of the apparatus may beevaluated later. The information stored locally can also be uploaded anddownloaded to and from the main database.

[0260] Although in the above example the main database and the localdatabase reside on separate computers, it may also be possible toimplement a system where both the main database and the local databaseresides on the same computer. The two database may both reside on thesystem control computer which is part of the liquid transfer apparatus,or they may both reside on a separate computer remotely and communicatewith the system control computer through a computer network (e.g.,Ethernet, wireless network). Alternatively, the main database and thelocal database may also be integrated into a single database.

[0261] One skilled in the art would appreciate that various otherdatabase structures are also possible. A production line of liquidtransfer apparatuses may be configured with a centralized system thatcontrols the various liquid transfer apparatuses. All the database maybe provided by the centralized database management system, andinformation generated by the local liquid transfer apparatus aretransferred back the central system. In an alternate design, each liquidtransfer apparatus may function independently with its own main databaseand its own local database. In another variation, the main databasereside on a centralized computer system that connects to all theassociated liquid transfer apparatuses and each liquid transferapparatus maintains its own local database. Database may be provided tothe computer system (either the central computer or the system controlcomputer resided on each liquid transfer apparatus) through variousportable memory storage device (e.g., magnetic disk, flash memory disk,CD-ROM, CD-RW, DVD disk, USB portable memory storage device) or it maybe transferred directly to the system through various electronicconnections or network (e.g., computer network, wireless network, IRport, Ethernet, USB connections). As one skilled in the art wouldappreciate, the output database may also be provided through variousportable memory storage devices or it may be transferred directly to aremote system through various electronic connections or networks.Alternatively, the output database may be stored in the local system forfuture access.

[0262] In another aspect, an error recovery protocol may be implementedto assist in the operation of the liquid transfer apparatus. The errorrecovery protocol may allow the liquid transfer apparatus to reducethroughput time (increase efficiency) and also to minimize the overallerrors found in the product (quality control). In one example of aliquid transfer process, the apparatus ejects a desired amount of fluidfrom each source well to a corresponding location on the target in apredetermined order. In the event that a transfer did not successfullyoccur (e.g., droplet did not eject, ejected droplet did not reach itsintended destination) during the process run, this error recoveryprotocol then commences. First, the location of the “missed” well isstored into a database. The apparatus does not attempt to retry the dropejection from the missed well at that point in time. The processcontinues to the next source well according to the original run order.If another failed drop ejection is detected, the location of that nextmissed well is also simply stored into a database. The process continuesagain. No attempt to retry drop ejection from the missed well is madeuntil the entire original run order is completed. Upon which, theapparatus will perform a series of re-tries on the missed wells listedin the database.

[0263] Alternatively, the apparatus may also support one or morerecovery modes. The recovery mode may be delayed,(retry after completionof the original run order, as mentioned above), or real time (immediateretry after detection of a missed well or missed transfer). For example,in one variation, the apparatus supports both the delayed and real-timerecovery modes. In this variation, immediately after the detection of amissed well the apparatus will retry the missed well. After one retry(or more than one retry, depending on the system setting), if the liquidtransfer is still not completed in that well, the apparatus will recordthe well as a missed well and move onto the next well. After the entireoriginal run order has been completed, the system controller willretrieve the “missed well” information from the database and retry themissed well.

[0264] However, in the event that the number of wells that fails toeject a drop (or fails to complete the transfer of liquid into theintended target well) exceeds a statistically significant number duringthe original run order, the apparatus may be determined that a machinesystem error is warranted. In that event, one or more procedures may beperformed in an attempt to restore the physical parameters of theapparatus back to an operational state. If unsuccessful, the machine maystop and signal the need for maintenance. But if successful, the missedwells recorded will be re-tried immediately after the machine systemerror is addressed by the system. Once these specific missed wells arerestored, the process run will resume according to the original runorder. If after the original run is completed and missed wells stillremain in the database, then those wells will then be re-tried at thistime. If recovery is still not successful, then those wells are recordedin the database for informational purpose, which may be applied in theanalysis and/or utilization when the target plate is utilized in futureprocessing or procedure. For example, if the target plate is beinganalyzed for chemical reactions after completion of liquid transfer, themissed well will be accounted for in the analysis procedure.

[0265] Other criteria that may be considered in determining the path ofthe error recovery system includes, but is not limited to, spotdetection, drop detection, liquid level detection, wave reflection, anddrop trajectory, drop speed, drop morphology, spot morphology, and spotlocation.

[i] Frame and Support Structure

[0266] In one variation, the liquid transfer apparatus is built upon aninternal skeleton-like framework 1902, as shown in FIG. 20. Thisframework may provide a rigid structure for which to attach all of thedevices and the sub-assemblies. The frame may have additional featuressuch as adjustable feet 1904 for leveling the entire system, casters foreasy placement, and/or floor anchors to securely hold the device inplace.

[0267] Panels may be provided to completely enclose the framework.Panels 1906 may be either hinged or removable to ease access to theapparatus' sub-assemblies for maintenance and/or repair. All panels maybe secured by a locking mechanism to prevent unauthorized access and toprovide protection to the operator from various hazardous, such aselectrical voltages and the moving mechanisms of the system.

[j] Environment and Safety Enclosure

[0268] An environmental enclosure 1 may be mounted directly to the frameof the liquid transfer system, as seen in FIG. 1. In one variation, itis comprised of a cabinet, a top cover, and front panels/doors.

[0269] The environmental enclosure may be configured to maintaintemperature and humidity inside the processing chamber. Alternatively,it may be configured to maintain an environment of an anhydrous gas,such as argon or nitrogen. In one variation, the environmental chamberis configured to maintain temperature, humidity, and an environment ofoxygen and carbon dioxide gas for cell or tissue incubation. It may alsobe equipped with a gas inlet device (rotometer) to meter the suppliedgas and maintain it at the desired level. An exhaust damper may beadapted in conjunction with the rotometer to control the gas exchangerate and the enclosure pressure. A small amount of gas may becontinuously vented out of the system to the exhaust duct. The exhaustduct may be connected to a separate exhaust system. In one variation,the magnehelic gauge may be configured to maintain the pressure insidethe chamber at a level below the ambient pressure to minimize the amountof gas escaping out of the chamber. The temperature and humidity controlpackage may include a dehumidification chiller, a heater, a waterinjection valve, two additional dampers, and/or a relative humidity andtemperature sensor. A chiller may be used to remove excess water fromthe circulating air (or gas) by cooling it below the dew point. Waterand/or frost collected by the chiller may be removed periodically by aheater built into the chiller. A series of dampers may be adapted todirect the circulating air to bypass the chiller during the waterremoval cycle. A heater may be utilized to warm the chilled,dehumidified air after it is re-mixed with the main air flow and beforethe re-circulating air is returned to the operations chamber. Ifhumidity need to be increased, the system controller may open a waterinjection valve to release water into a pan above the heater. Evaporatedwater from the pan may increases the humidity of the air or gasreturning to the operations chamber. A relative humidity and temperaturesensor may be implemented to control the temperature of the heater, thechiller, the dehumidification chiller, and/or the electric heater, tomaintain the environment at a preset temperature and relative humidity.

Applications of the Invention

[0270] The liquid transfer apparatus described above may be utilized invarious high throughput biological, chemical, and biochemical processesthat require efficient transfer of small quantities of liquid. Selectiveexamples of biochemical synthesis and screening applications aredescribed below for illustration purpose only. It is understood thatthese examples are not intend to be limiting and the present inventionmay be applicable in various biological, chemical, and biochemicalapplications, as one skilled in the art would appreciate.

[0271] Source fluids contemplated for use in the practice of the presentinvention may comprise one or more source materials. Source materialsmay include both biological and chemical compounds, agents and lifeforms (e.g., plant cells, eukaryotic or prokaryotic cells).

[0272] As used herein, “biological compounds” may comprise nucleic acids(e.g., polynucleotides), peptides and polypeptides (including antibodiesand fragments of antibodies), carbohydrates (e.g., oligosaccharides),and combinations thereof. In some variations, cells (e.g., eukaryotic orprokaryotic) may be contained in the fluid. Such an arrangement mayallow for the transfer of organisms from one source fluid to anotherfluid or target during cell culturing or sorting.

[0273] The term “polynucleotides” and “oligonucleotides” include two ormore nucleotide bases (e.g., deoxyribonucleic acids or ribonucleicacids) linked by a phosphodiester bond. Accordingly, suchpolynucleotides and oligonucleotides include DNA, cDNA and RNAsequences. Polynucleotides and oligonucleotides may comprise nucleotideanalogs, substituted nucleotides, and the like. Nucleic acidscontemplated for use in the practice of the present invention includenaked DNA, naked RNA, naked plasmid DNA, either supercoiled or linear,and encapsulated DNA or RNA (e.g., in liposomes, microspheres, or thelike). As will be understood by those of skill in the art, particlesmixed with plasmid so as to “condense” the DNA molecule may also beemployed.

[0274] Polypeptides contemplated for use in the practice of the presentinvention include two or more amino acids joined to one another bypeptide bonds. Thus, polypeptides include proteins (e.g., enzymes (e.g.,DNA polymerase), structural proteins (e.g., keratin), antibodies,fragments thereof, and the like), prions, and the like.

[0275] “Chemical compounds” contemplated for use in the practice of thepresent invention may comprise any compound that does not fall under thedefinition of biological compounds as used herein. Specific chemicalcompounds contemplated for use in the practice of the present inventionincludes dyes, detectable labels, non-enzyme chemical reagents,diluents, and the like.

[0276] As used herein, the terms “detectable label”, “indicating group”,“indicating label” and grammatical variations thereof refer to singleatoms and molecules that are either directly or indirectly involved inthe production of a detectable signal. Any label or indicating agent canbe linked to or incorporated in a nucleic acid, a polypeptide,polypeptide fragment, antibody molecule or fragment thereof and thelike. These atoms or molecules can be used alone or in conjunction withadditional reagents. Such labels are themselves well known in the art.

[0277] The detectable label can be a fluorescent-labeling agent thatchemically binds to proteins without denaturation to form a fluorochrome(dye) that is a useful immunofluorescent tracer. Suitable fluorescentlabeling agents are fluorochromes such as fluorescein isocyanate (FIC),fluorescein isothiocyanate (FITC),5-dimethylamine-1-naphthalenesulfonylchloride (DANSC),tetramethylrhodamine isothiocyanate (TRITC), lissamine, rhodamine 8200sulphonyl chloride (RB-200-SC), and the like. A description ofimmunofluorescence analytic techniques is found in DeLuca,“Immunofluorescence Analysis”, in Antibody as a Tool, Marchalonis etal., eds., John Wiley & Sons, Ltd., pp. 189-231 (1982), which isincorporated herein by reference.

[0278] The detectable label may be an enzyme, such as horseradishperoxidase (HRP), glucose oxidase, and the like. In such cases where theprincipal indicating label is an enzyme, additional reagents arerequired for the production of a visible signal. Such additionalreagents for HRP include hydrogen peroxide and an oxidation dyeprecursor such as diaminobenzidine. An additional reagent useful withglucose oxidase is 2,2′-azino-di-(3-ethyl-benzthiazoline-G-sulfonicacid) (ABTS).

[0279] In another variation, radioactive elements are employed aslabeling agents. An exemplary radiolabeling agent is a radioactiveelement that produces gamma ray emissions, positron emissions, or betaemissions. Elements that emit gamma rays, such as 124I, 125I, 126I, 131Iand 51Cr, represent one class of radioactive element indicating groups.Beta emitters include 32P, 111Indium, 3H and the like.

[0280] The linking of a label to a substrate (e.g., labeling of nucleicacids, antibodies, polypeptides, proteins, and the like), is well knownin the art. For instance, antibody molecules can be labeled by metabolicincorporation of radiolabeled amino acids provided in the culturemedium. See, for example, Galfre et al., Methods of Enzymology, 73:3-46(1981). Conventional means of protein conjugation or coupling byactivated functional groups are particularly applicable. See, forexample, Aurameas et al., Scandinavia Journal of Immunology. Vol. 8,Suppl. 7:7-23 (1978), Rodwell et al., Biotech., 3:889-894 (1984), andU.S. Pat. No. 4,493,795.

[0281] In one variation, the methods of the present invention may beused to pair certain ligands (i.e., a molecular group that binds toanother entity to form a larger more complex entity) and bindingpartners for such ligands. For example, certain biological molecules areknown to interact and bind to other molecules in a very specific manner.Essentially molecules having a high binding specificity or affinity foreach other can be considered a ligand/binding partner pair, e.g., avitamin binding to a protein, a hormone binding to a cell-surfacereceptor, a drug binding to a cell-surface receptor, a glycoproteinserving to identify a particular cell to its neighbors, an antibody(e.g., IgG-class) binding to an antigenic determinant, anoligonucleotide sequence binding to its complementary fragment of RNA orDNA, and the like.

[0282] Such pairings are useful in screening techniques, synthesistechniques, and the like. Accordingly, in one embodiment of the presentinvention, screening assays may be performed in which the bindingspecificity of one compound for another is sought to be determined. Forexample, multiple test compounds (i.e., putative ligands, optionallyhaving detectable labels attached) may be screened for specificinteraction with a selected binding partner. Such assays may be carriedout by positioning one of a plurality of putative ligands in each poolof an array of source fluids. The target may comprise, for example, anarray of target zones, each zone having affixed to it a sample of thebinding partner for which specific binding is sought to be identified.Employing the methods of the invention, a droplet of each putativeligand can be ejected to a target zone and the target thereafter washedunder defined conditions. Afterwards, each of the target zones isinspected to determine whether binding of the putative ligand hasoccurred. Binding of a putative ligand serves to identify that compoundas a ligand for the binding partner. Binding can easily be identified byany method known to those of skill in the art. By employing detectablelabeled test compounds, binding can readily be determined by identifyinga labeled compound bound to the target. Of course, such assays may bereversed, i.e., the selected binding partner may be used as a labeledsource compound, while putative ligands are arrayed onto the target.

[0283] In another variation, the methods of the invention may also beapplied to the identification of peptides or peptide mimetics that bindbiologically important receptors. In this variation, a plurality ofpeptides of known sequence can be applied to a target to form an arrayusing methods described herein. The resulting array of peptides can thenbe used in binding assays with selected receptors (or other bindingpartners) to screen for peptide mimetics of receptor agonists andantagonists. Thus, the invention provides a method for producing peptidearrays on a target, and methods of using such peptide arrays to screenfor peptide mimetics of receptor agonists and antagonists.

[0284] The specific binding properties of binding partners to ligandshave implications for many fields. For example, the strong bindingaffinity of antibodies for specific antigenic determinants is criticalto the field of immunodiagnostics. Additionally, pharmaceutical drugdiscovery, in many cases, involves discovering novel drugs havingdesirable patterns of specificity for naturally occurring receptors orother biologically important binding partners. Many other areas ofresearch exist in which the selective interaction of binding partnersfor ligands is important and are readily apparent to those skilled inthe art.

[0285] The invention may also be employed in synthesis reactions. Forexample, in another embodiment of the present invention, employingmonomeric and/or multimeric nucleotides as source compounds can beemployed to synthesize oligonucleotides (useful as probes, labels,primers, anti-sense molecules, and the like). Such source compounds maybe present in a fluid medium (i.e., source fluid) and each source fluidplaced in a defined position of an array on the source containmentstructure. By ejecting source nucleotides from the source containmentstructure onto a defined target zone of the target, defined nucleotidescan be added to a growing product oligonucleotide chain in an additivemanner that serves to define the nucleotide sequence of the growingproduct oligonucleotide.

[0286] The particular chemical reactions necessary to performoligonucleotide synthesis are well known to those of skill in the art.Such reactions, or others, which may become known, can be performed insitu on the target by, for example, contacting the growingoligonucleotide with the necessary reagents between each iterativeaddition of further nucleotide(s). Flowing the reagents across thetarget, by passing the target through a reagent bath, or the like canperform reagent contacting. By employing a target with a suitablecoating or having suitable surface properties, the growingoligonucleotide can be bound to the target with sufficient strength toundergo the necessary chemical reactions, after which the matureoligonucleotide can be released from the target. For example, methodsfor attaching oligonucleotides to glass plates in a manner suitable foroligonucleotide synthesis are known in the art. Southern, Chem. abst.113; 152979r (1990), incorporated by reference herein in its entirety,describes a stable phosphate ester linkage for permanent attachment ofoligonucleotides to a glass surface. Mandenius et al., Anal. Biochem.157; 283 (1986), incorporated by reference herein in its entirety,teaches that the hydroxyalkyl group resembles the 5′-hydroxyl ofoligonucleotides and provides a stable anchor on which to initiate solidphase synthesis. Other such binding/release technologies are also knownor may become available and are thus contemplated for use in thepractice of the present invention.

[0287] All publications and patent applications cited in thisspecification are herein incorporated by reference in their entirety asif each individual publication or patent application were specificallyand individually put forth in the text below.

[0288] This invention has been described and specific examples of theinvention have been portrayed. The use of those specifics is notintended to limit the invention in anyway. Additionally, to the extentthere are variations of the invention, which are within the spirit ofthe disclosure or equivalent to the inventions found in the claims, itis our intent that this patent will cover those variations as well.

I claim the following:
 1. A wave-guide assembly comprising: awave-guide; a structure having a suction channel for removing excesscoupling liquid from area surrounding the distal end of said wave-guide,wherein said wave-guide is moveably disposed within said structure; anda fluid channel within said structure for supplying a coupling liquid toa distal end of said wave-guide.
 2. A wave-guide assembly of claim 1further comprising: a piezoelectric transducer attached to a proximalend of said wave-guide.
 3. A wave-guide assembly of claim 2 wherein thedistal end of said wave-guide has a lens-shaped tip.
 4. A wave-guideassembly of claim 1 wherein said wave-guide is configured to eject adroplet of liquid about 10 micro-liter or less.
 5. The wave-guideassembly of claim 1 wherein: said structure comprises an object having acylindrical lumen, a hollow elongated cylinder positioned within saidcylindrical lumen, wherein a inner surface of said cylindrical lumen anda outer surface of said hollow elongated cylinder defines said suctionchannel; and said wave-guide moveably disposed within said hollowelongated cylinder, wherein an inner surface of said hollow elongatedcylinder and a outer surface of said wave-guide defines said fluidchannel.
 6. The wave-guide assembly of claim 5 further comprising: afluid source connected to said fluid channel.
 7. The wave-guide assemblyof claim 5 further comprising: a suction generator connected to saidsuction channel.
 8. The wave-guide assembly of claim 5 furthercomprising: a suction source connected to said suction channel.
 9. Thewave-guide assembly of claim 7 further comprising: a fluid pumpconnected to said fluid channel for supplying coupling liquid to thedistal end of said wave-guide.
 10. The wave-guide assembly of claim 9further comprising: a fluid displacement device connected to said fluidchannel for adjusting a volume of coupling liquid at the distal end ofsaid wave-guide.
 11. The wave-guide assembly of claim 10 wherein saidfluid displacement device is coupled to said wave-guide.
 12. Thewave-guide assembly of claim 10 wherein said fluid displacement devicecomprises a piston pump.
 13. The wave-guide assembly of claim 12 furthercomprising: a wave-guide support connected to said wave-guide, wherein aportion of said wave-guide support and said piston pump are connected toone another.
 14. The wave-guide assembly of claim 9 further comprising:a fluid reservoir connected to said fluid pump; and a tubing connectingsaid suction generator to said fluid reservoir.
 15. The wave-guideassembly of claim 7 further comprising: said coupling liquid locatedwithin said fluid channel.
 16. The wave-guide assembly of claim 15wherein said coupling liquid consists essentially of water.
 17. Thewave-guide assembly of claim 5 wherein said structure further comprisesa trough on an outer perimeter of said structure adapted for collectingfluids on an upper surface of said trough.
 18. The wave-guide assemblyof claim 17 further comprising: a drain channel connecting said suctiongenerator to the upper surface of said trough.
 19. The wave-guideassembly of claim 17 further comprising: a second suction generatorconnected to said upper surface of said trough.
 20. The wave-guideassembly of claim 2 further comprising: a frame coupled to saidstructure, wherein said frame is adapted to allow sufficient movement ofthe structure as said wave-guide is moved vertically to prevent bindingof said wave-guide against said structure.
 21. The wave-guide assemblyof claim 20 further comprising: a carriage connected to said frame formoving said frame and said structure in the vertical direction.
 22. Thewave-guide assembly of claim 2 further comprising: a support coupled tosaid structure, wherein said supporting apparatus is adapted to allowsufficient movement of the structure as said wave-guide is movedvertically to prevent binding of said wave-guide against said structure.23. The wave-guide assembly of claim 22 further comprising: a lineardisplacement device coupled to said supporting apparatus for moving saidsupporting apparatus in the vertical direction.
 24. The wave-guideassembly of claim 5 further comprising: a frame, wherein said structureis coupled to said frame such that said structure may move along the X/Yplane of said frame and not along the Z-axis of said frame.
 25. Thewave-guide assembly of claim 24, wherein the movement along the X[Yplane is limited to about 1 mm along the X-axis and about 1 mm along theY-axis.
 26. The wave-guide assembly of claim 5 further comprising: astage for holding and moving a fluid container above said structure,said stage is adapted to maintain a constant vertical distance betweensaid structure and said fluid container while said stage is moving in anX/Y plane.
 27. The wave-guide assembly of claim 26 further comprising: afluid container having a plurality of wells, wherein said fluidcontainer is placed on said stage.
 28. The wave-guide assembly of claim27 further comprising: a coupling liquid, wherein said coupling liquidis in contact with said wave-guide and the bottom surface of said fluidcontainer.
 29. The wave-guide assembly of claim 5 wherein saidwave-guide assembly is configured to maintain a liquid contact with afluid containment structure as the wave-guide moves vertically.
 30. Thewave-guide assembly of claim 5 further comprising: a trough surroundingsaid first cylindrical body, wherein said trough is connected to saidcylindrical body; a fluid pump connected to said fluid channel; anegative pressure generator connected to said suction channel; a pistonpump connected to said fluid channel; a piezoelectric transducerconnected to said wave-guide; a frame, wherein said structure is coupledto said frame such that said structure may move in an X-Y plane of saidframe but may not move in the Z direction; and a motor coupled to saidwave-guide for moving the wave-guide in a vertical direction within saidstructure.
 31. The wave-guide assembly of claim 1 wherein said fluidchannel surrounds said wave-guide, and said suction channel surroundssaid fluid channel.
 32. A wave-guide assembly of claim 31 furthercomprising: a fluid source connected to said fluid channel; and anegative pressure generator connected to said suction channel.
 33. Thewave-guide assembly of claim 32 further comprising: an acoustic waveemitter connected to said wave-guide.
 34. The wave-guide assembly ofclaim 32 further comprising: a trough surrounding said suction channel.35. The wave-guide assembly of claim 34 further comprising: a drainagechannel within said structure, said drainage channel is connected tosaid trough for draining fluids from said trough.
 36. The wave-guideassembly of claim 33 further comprising: a coupling liquid, wherein saidcoupling liquid is positioned on the distal end of said wave-guide. 37.The wave-guide assembly of claim 36 further comprising: a fluidcontainer having a bottom surface and moveably disposed above saidwave-guide such that said coupling liquid is positioned between saidwave-guide and said fluid container, and said coupling liquid comes intocontact with both the wave-guide and the bottom surface of said fluidcontainer, said fluid container further having a plurality of wellslocated in said fluid container.
 38. The wave-guide assembly of claim 33further comprising: a fluid displacement device connected to said fluidchannel for displacing a volume of said coupling liquid at a distal tipof said wave-guide.
 39. The wave-guide assembly of claim 38 wherein saidfluid source comprises a fluid pump connected to a fluid reservoir. 40.The wave-guide assembly of claim 1 wherein said fluid channel has anoutlet located next to a distal end of said wave-guide, and said suctionchannel has an inlet located next to the outlet of said fluid channel.41. The wave-guide assembly of claim 40 further comprising: a fluidsource connected to said fluid channel; and a suction generatorconnected to said suction channel.
 42. The wave-guide assembly of claim41 wherein the inlet of said suction channel surrounds the distal end ofsaid wave-guide.
 43. The wave-guide assembly of claim 1 wherein saidstructure has a lumen, a distal end and a proximal end, a cavity locatednext to an opening of said lumen at the distal end of said structure,said fluid channel running from said lumen to an inlet, said suctionchannel running from said cavity to an outlet, said wave-guide ismoveably disposed within said lumen.
 44. The wave-guide assembly ofclaim 43 further comprising: a negative pressure generator connected tosaid outlet; a fluid source connected to said inlet; and an acousticwave generator connected to said wave-guide.
 45. The wave-guide assemblyof claim 44 further comprising: a frame, wherein said structure iscoupled to said frame such that said structure may only move in the Xaxis and Y axis direction and not in the Z axis direction.
 46. Thewave-guide assembly of claim 1 further comprising: a fluid displacementdevice connected to said fluid channel, wherein said fluid displacementdevice is adapted to adjust the volume of coupling liquid at the distalend of said wave-guide.
 47. The wave-guide assembly of claim 1 furthercomprising: a piston pump coupled to said wave-guide.
 48. A method ofisolating a liquid coupling medium at a tip of an acoustic wave-guidecomprising the steps of: supplying a volume of the liquid couplingmedium for coupling the acoustic wave-guide with a fluid containmentstructure; and localizing the liquid coupling medium to a distal end ofsaid acoustic wave-guide.
 49. The method of claim 48 further comprising:compensating for a vertical motion of said wave-guide by adjusting thevolume of the liquid coupling medium simultaneously with movement of thewave-guide.
 50. The method of claim 48 wherein: the localizing stepcomprises maintaining a suction in the area surrounding the distal endof said wave-guide, wherein excess coupling liquid is captured andremoved by said suction.
 51. The method of claim 50 further comprisingthe step of: positioning the fluid containment structure above saidwave-guide such that said coupling liquid is positioned between saidwave-guide and said fluid containment structure, and said couplingliquid contacts said wave-guide and said fluid containment structure,wherein said fluid containment structure has a source fluid containedwithin said structure.
 52. The method of claim 51 further comprising thestep of: propagating an acoustic wave of sufficient intensity andstrength through said wave-guide, said coupling liquid, said sourcefluid containment structure and into said source fluid, to eject aportion of said source fluid.
 53. The method of claim 50 wherein thelocalizing step comprises maintaining a continuous suction in the areasurrounding the distal end of said wave-guide, the supplying stepcomprises supplying a continuous flow of coupling liquid to the distalend of said wave-guide.
 54. The method of claim 52 wherein the fluidcontainment structure comprises a structure having a plurality of wells,and at least two of the wells contain source fluids.
 55. The method ofclaim 52 wherein the propagating step further comprises: adjusting theposition of the wave-guide in a vertical direction; adjusting the volumeof the coupling liquid between said wave-guide and said fluidcontainment structure such that the coupling liquid maintains contactwith both the wave-guide and the bottom surface of said fluidcontainment structure; and propagating an acoustic wave through saidwave-guide, said coupling liquid, said fluid containment structure andinto said source fluid.
 56. The method of claim 55 wherein the steps ofadjusting the position of the wave-guide and adjusting the volume of thecoupling liquid occurs simultaneously.
 57. The method of claim 54further comprising the steps of: moving the position of the source fluidcontainment structure laterally so that a second well is positionedabove the wave-guide, wherein said second well having a second sourcefluid; and propagating an acoustic wave through said wave-guide, saidcoupling liquid, said fluid containment structure and into said secondsource fluid.
 58. The method of claim 48 further comprising: adjustingthe position of the wave-guide in a vertical direction; and adjustingthe volume of the coupling liquid between said wave-guide and said fluidcontainment structure such that the coupling liquid maintains contactwith both the wave-guide and the fluid containment structure.
 59. Themethod of claim 58 wherein the steps of adjusting the position of thewave-guide and adjusting the volume of the coupling liquid occurssimultaneously.